diff --git a/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredRuleClassProvider.java b/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredRuleClassProvider.java
index 2f4f86e..a94134f 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredRuleClassProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredRuleClassProvider.java
@@ -29,6 +29,7 @@
 import com.google.devtools.build.lib.analysis.config.ConfigurationFragmentFactory;
 import com.google.devtools.build.lib.analysis.config.DefaultsPackage;
 import com.google.devtools.build.lib.analysis.config.FragmentOptions;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.graph.Digraph;
 import com.google.devtools.build.lib.graph.Node;
@@ -255,7 +256,7 @@
     public Label load(String from) {
       try {
         return Label.parseAbsolute(from);
-      } catch (Label.SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         throw new IllegalArgumentException(from);
       }
     }
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/LabelExpander.java b/src/main/java/com/google/devtools/build/lib/analysis/LabelExpander.java
index 89ce2e7..9c16308 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/LabelExpander.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/LabelExpander.java
@@ -19,6 +19,7 @@
 import com.google.common.base.Strings;
 import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.syntax.Label;
 import com.google.devtools.build.lib.vfs.PathFragment;
 
@@ -154,7 +155,7 @@
   private static Label resolveLabelText(String labelText, Label labelResolver) {
     try {
       return labelResolver.getRelative(labelText);
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       // It's a heuristic, so quietly ignore "errors". Because Label.getRelative never
       // returns null, we can use null to indicate an error.
       return null;
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/LocationExpander.java b/src/main/java/com/google/devtools/build/lib/analysis/LocationExpander.java
index 04c2d5a..26b0f8c 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/LocationExpander.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/LocationExpander.java
@@ -23,6 +23,7 @@
 import com.google.common.collect.Sets;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.packages.OutputFile;
 import com.google.devtools.build.lib.packages.Type;
 import com.google.devtools.build.lib.syntax.Label;
@@ -212,7 +213,7 @@
   private Label parseLabel(String labelText, String message, ErrorReporter reporter) {
     try {
       return ruleContext.getLabel().getRelative(labelText);
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       reporter.report(ruleContext, String.format("invalid label%s: %s", message, e.getMessage()));
       return null;
     }
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/RuleDefinitionEnvironment.java b/src/main/java/com/google/devtools/build/lib/analysis/RuleDefinitionEnvironment.java
index 4dcd080..1f00eca 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/RuleDefinitionEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/RuleDefinitionEnvironment.java
@@ -23,9 +23,7 @@
 public interface RuleDefinitionEnvironment {
   /**
    * Parses the given string as a label and returns the label, by calling {@link
-   * Label#parseAbsolute}. Instead of throwing a {@link
-   * com.google.devtools.build.lib.syntax.Label.SyntaxException}, it throws an {@link
-   * IllegalArgumentException}, if the parsing fails.
+   * Label#parseAbsolute}. Throws a {@link IllegalArgumentException} if the parsing fails.
    */
   Label getLabel(String labelValue);
 }
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
index 485786f..4ea1509 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
@@ -38,6 +38,7 @@
 import com.google.devtools.build.lib.analysis.DependencyResolver;
 import com.google.devtools.build.lib.analysis.ViewCreationFailedException;
 import com.google.devtools.build.lib.analysis.config.BuildConfigurationCollection.Transitions;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.packages.Attribute;
@@ -52,7 +53,6 @@
 import com.google.devtools.build.lib.packages.Target;
 import com.google.devtools.build.lib.rules.test.TestActionBuilder;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.syntax.SkylarkCallable;
 import com.google.devtools.build.lib.syntax.SkylarkModule;
 import com.google.devtools.build.lib.syntax.SkylarkModuleNameResolver;
@@ -286,7 +286,7 @@
           input = "//" + input;
         }
         return Label.parseAbsolute(input);
-      } catch (SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         throw new OptionsParsingException(e.getMessage());
       }
     }
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/DefaultsPackage.java b/src/main/java/com/google/devtools/build/lib/analysis/config/DefaultsPackage.java
index e046330..e702ac2 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/DefaultsPackage.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/DefaultsPackage.java
@@ -18,8 +18,8 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 
 import java.util.Locale;
 import java.util.Map;
@@ -161,7 +161,7 @@
     if (value.startsWith("//")) {
       try {
         return Label.parseAbsolute(value);
-      } catch (SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         // We ignore this exception here - it will cause an error message at a later time.
         return null;
       }
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/FragmentOptions.java b/src/main/java/com/google/devtools/build/lib/analysis/config/FragmentOptions.java
index c7b8c47..677aa34 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/FragmentOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/FragmentOptions.java
@@ -17,9 +17,9 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Multimap;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.packages.Attribute.SplitTransition;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.common.options.Options;
 import com.google.devtools.common.options.OptionsBase;
 
@@ -115,7 +115,7 @@
     if ((value != null) && value.startsWith("//")) {
       try {
         return Label.parseAbsolute(value);
-      } catch (SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         // We ignore this exception here - it will cause an error message at a later time.
         // TODO(bazel-team): We can use a Converter to check the validity of the crosstoolTop
         // earlier.
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/PackageProviderForConfigurations.java b/src/main/java/com/google/devtools/build/lib/analysis/config/PackageProviderForConfigurations.java
index 83b4715..d6846ef 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/PackageProviderForConfigurations.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/PackageProviderForConfigurations.java
@@ -15,9 +15,9 @@
 
 import com.google.devtools.build.lib.analysis.BlazeDirectories;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration.Fragment;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.packages.Package;
 import com.google.devtools.build.lib.pkgcache.LoadedPackageProvider;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 
 import java.io.IOException;
 
@@ -29,7 +29,7 @@
    * Adds dependency to fileName if needed. Used only in skyframe, for creating correct dependencies
    * for {@link com.google.devtools.build.lib.skyframe.ConfigurationCollectionValue}.
    */
-  void addDependency(Package pkg, String fileName) throws SyntaxException, IOException;
+  void addDependency(Package pkg, String fileName) throws LabelSyntaxException, IOException;
   
   /**
    * Returns fragment based on fragment type and build options.
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/RunUnderConverter.java b/src/main/java/com/google/devtools/build/lib/analysis/config/RunUnderConverter.java
index 8da1fbb..951c478 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/RunUnderConverter.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/RunUnderConverter.java
@@ -13,10 +13,10 @@
 // limitations under the License.
 package com.google.devtools.build.lib.analysis.config;
 
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.shell.ShellUtils;
 import com.google.devtools.build.lib.shell.ShellUtils.TokenizationException;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.common.options.Converter;
 import com.google.devtools.common.options.OptionsParsingException;
 
@@ -44,7 +44,7 @@
       try {
         final Label runUnderLabel = Label.parseAbsolute(runUnderCommand);
         return new RunUnderLabel(input, runUnderLabel, runUnderList);
-      } catch (SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         throw new OptionsParsingException("Not a valid label " + e.getMessage());
       }
     } else {
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryFunction.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryFunction.java
index c8605b8..4bf10f7 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryFunction.java
@@ -17,7 +17,6 @@
 import com.google.common.base.Preconditions;
 import com.google.devtools.build.lib.analysis.BlazeDirectories;
 import com.google.devtools.build.lib.analysis.RuleDefinition;
-import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier.RepositoryName;
 import com.google.devtools.build.lib.packages.AggregatingAttributeMapper;
 import com.google.devtools.build.lib.packages.BuildFileContainsErrorsException;
@@ -255,8 +254,7 @@
   public static Rule getRule(
       RepositoryName repositoryName, @Nullable String ruleClassName, Environment env)
       throws RepositoryFunctionException {
-    SkyKey packageKey = PackageValue.key(
-        PackageIdentifier.createInDefaultRepo(ExternalPackage.NAME));
+    SkyKey packageKey = PackageValue.key(ExternalPackage.PACKAGE_IDENTIFIER);
     PackageValue packageValue;
     try {
       packageValue = (PackageValue) env.getValueOrThrow(packageKey,
@@ -327,7 +325,8 @@
   }
 
   public static Path getExternalRepositoryDirectory(BlazeDirectories directories) {
-    return directories.getOutputBase().getRelative(ExternalPackage.NAME);
+    return directories.getOutputBase().getRelative(
+        ExternalPackage.PACKAGE_IDENTIFIER.getPackageFragment());
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/LabelSyntaxException.java b/src/main/java/com/google/devtools/build/lib/cmdline/LabelSyntaxException.java
new file mode 100644
index 0000000..3c66959
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/LabelSyntaxException.java
@@ -0,0 +1,24 @@
+// Copyright 2015 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.cmdline;
+
+/**
+ * Thrown by the parsing methods to indicate a bad label.
+ */
+public class LabelSyntaxException extends Exception {
+  public LabelSyntaxException(String message) {
+    super(message);
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/PackageIdentifier.java b/src/main/java/com/google/devtools/build/lib/cmdline/PackageIdentifier.java
index 8867c98..9d0ef0e 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/PackageIdentifier.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/PackageIdentifier.java
@@ -55,12 +55,12 @@
           .build(
               new CacheLoader<String, RepositoryName> () {
                 @Override
-                public RepositoryName load(String name) throws TargetParsingException {
+                public RepositoryName load(String name) throws LabelSyntaxException {
                   String errorMessage = validate(name);
                   if (errorMessage != null) {
                     errorMessage = "invalid repository name '"
                         + StringUtilities.sanitizeControlChars(name) + "': " + errorMessage;
-                    throw new TargetParsingException(errorMessage);
+                    throw new LabelSyntaxException(errorMessage);
                   }
                   return new RepositoryName(StringCanonicalizer.intern(name));
                 }
@@ -70,11 +70,11 @@
      * Makes sure that name is a valid repository name and creates a new RepositoryName using it.
      * @throws TargetParsingException if the name is invalid.
      */
-    public static RepositoryName create(String name) throws TargetParsingException {
+    public static RepositoryName create(String name) throws LabelSyntaxException {
       try {
         return repositoryNameCache.get(name);
       } catch (ExecutionException e) {
-        Throwables.propagateIfInstanceOf(e.getCause(), TargetParsingException.class);
+        Throwables.propagateIfInstanceOf(e.getCause(), LabelSyntaxException.class);
         throw new IllegalStateException("Failed to create RepositoryName from " + name, e);
       }
     }
@@ -97,11 +97,6 @@
         return "workspace name must start with '@'";
       }
 
-      // "@" isn't a valid workspace name.
-      if (name.length() == 1) {
-        return "empty workspace name";
-      }
-
       // Check for any character outside of [/0-9A-Za-z_.-]. Try to evaluate the
       // conditional quickly (by looking in decreasing order of character class
       // likelihood).
@@ -174,11 +169,13 @@
 
   public static final String DEFAULT_REPOSITORY = "";
   public static final RepositoryName DEFAULT_REPOSITORY_NAME;
+  public static final RepositoryName MAIN_REPOSITORY_NAME;
 
   static {
     try {
       DEFAULT_REPOSITORY_NAME = RepositoryName.create(DEFAULT_REPOSITORY);
-    } catch (TargetParsingException e) {
+      MAIN_REPOSITORY_NAME = RepositoryName.create("@");
+    } catch (LabelSyntaxException e) {
       throw new IllegalStateException(e);
     }
   }
@@ -205,7 +202,7 @@
         throws IOException, ClassNotFoundException {
       try {
         packageId = new PackageIdentifier((String) in.readObject(), (PathFragment) in.readObject());
-      } catch (TargetParsingException e) {
+      } catch (LabelSyntaxException e) {
         throw new IOException("Error serializing package identifier: " + e.getMessage());
       }
     }
@@ -228,7 +225,7 @@
   public static PackageIdentifier createInDefaultRepo(PathFragment name) {
     try {
       return new PackageIdentifier(DEFAULT_REPOSITORY, name);
-    } catch (TargetParsingException e) {
+    } catch (LabelSyntaxException e) {
       throw new IllegalArgumentException("could not create package identifier for " + name
           + ": " + e.getMessage());
     }
@@ -243,7 +240,7 @@
   /** The name of the package. Canonical (i.e. x.equals(y) <=> x==y). */
   private final PathFragment pkgName;
 
-  public PackageIdentifier(String repository, PathFragment pkgName) throws TargetParsingException {
+  public PackageIdentifier(String repository, PathFragment pkgName) throws LabelSyntaxException {
     this(RepositoryName.create(repository), pkgName);
   }
 
@@ -254,13 +251,15 @@
     this.pkgName = Canonicalizer.fragments().intern(pkgName.normalize());
   }
 
-  public static PackageIdentifier parse(String input) throws TargetParsingException {
+  public static PackageIdentifier parse(String input) throws LabelSyntaxException {
     String repo;
     String packageName;
     int packageStartPos = input.indexOf("//");
-    if (packageStartPos > 0) {
+    if (input.startsWith("@") && packageStartPos > 0) {
       repo = input.substring(0, packageStartPos);
       packageName = input.substring(packageStartPos + 2);
+    } else if (input.startsWith("@")) {
+      throw new LabelSyntaxException("invalid package name '" + input + "'");
     } else if (packageStartPos == 0) {
       repo = PackageIdentifier.DEFAULT_REPOSITORY;
       packageName = input.substring(2);
@@ -271,12 +270,12 @@
 
     String error = RepositoryName.validate(repo);
     if (error != null) {
-      throw new TargetParsingException(error);
+      throw new LabelSyntaxException(error);
     }
 
     error = LabelValidator.validatePackageName(packageName);
     if (error != null) {
-      throw new TargetParsingException(error);
+      throw new LabelSyntaxException(error);
     }
 
     return new PackageIdentifier(repo, new PathFragment(packageName));
diff --git a/src/main/java/com/google/devtools/build/lib/packages/ConstantRuleVisibility.java b/src/main/java/com/google/devtools/build/lib/packages/ConstantRuleVisibility.java
index bb64015..8d50693 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/ConstantRuleVisibility.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/ConstantRuleVisibility.java
@@ -14,6 +14,7 @@
 package com.google.devtools.build.lib.packages;
 
 import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
 import com.google.devtools.build.lib.syntax.Label;
@@ -43,7 +44,7 @@
       PUBLIC_LABEL = Label.parseAbsolute("//visibility:public");
       LEGACY_PUBLIC_LABEL = Label.parseAbsolute("//visibility:legacy_public");
       PRIVATE_LABEL = Label.parseAbsolute("//visibility:private");
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new IllegalStateException();
     }
   }
diff --git a/src/main/java/com/google/devtools/build/lib/packages/ExternalPackage.java b/src/main/java/com/google/devtools/build/lib/packages/ExternalPackage.java
index cfb8143..fdb63e2 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/ExternalPackage.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/ExternalPackage.java
@@ -18,16 +18,15 @@
 import com.google.common.base.Verify;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Maps;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier.RepositoryName;
-import com.google.devtools.build.lib.cmdline.TargetParsingException;
 import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.events.StoredEventHandler;
 import com.google.devtools.build.lib.packages.RuleFactory.InvalidRuleException;
 import com.google.devtools.build.lib.syntax.Environment;
 import com.google.devtools.build.lib.syntax.FuncallExpression;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.vfs.Path;
 
 import java.util.Map;
@@ -36,9 +35,15 @@
  * This creates the //external package, where targets not homed in this repository can be bound.
  */
 public class ExternalPackage extends Package {
-  public static final String NAME = "external";
-  public static final PackageIdentifier PACKAGE_IDENTIFIER =
-      PackageIdentifier.createInDefaultRepo(NAME);
+  public static final PackageIdentifier PACKAGE_IDENTIFIER;
+
+  static {
+    try {
+      PACKAGE_IDENTIFIER = PackageIdentifier.parse("//external");
+    } catch (LabelSyntaxException e) {
+      throw new IllegalStateException();
+    }
+  }
 
   private Map<RepositoryName, Rule> repositoryMap;
 
@@ -133,15 +138,16 @@
      */
     public Builder createAndAddRepositoryRule(RuleClass ruleClass, RuleClass bindRuleClass,
         Map<String, Object> kwargs, FuncallExpression ast, Environment env)
-        throws InvalidRuleException, NameConflictException, SyntaxException, InterruptedException {
+        throws InvalidRuleException, NameConflictException, LabelSyntaxException,
+            InterruptedException {
       StoredEventHandler eventHandler = new StoredEventHandler();
       Rule tempRule = RuleFactory.createRule(
           this, ruleClass, kwargs, eventHandler, ast, ast.getLocation(), env);
       addEvents(eventHandler.getEvents());
       try {
         repositoryMap.put(RepositoryName.create("@" + tempRule.getName()), tempRule);
-      } catch (TargetParsingException e) {
-        throw new SyntaxException(e.getMessage());
+      } catch (LabelSyntaxException e) {
+        throw new LabelSyntaxException(e.getMessage());
       }
       for (Map.Entry<String, Label> entry :
         ruleClass.getExternalBindingsFunction().apply(tempRule).entrySet()) {
diff --git a/src/main/java/com/google/devtools/build/lib/packages/License.java b/src/main/java/com/google/devtools/build/lib/packages/License.java
index f4e554e..98ed31d 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/License.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/License.java
@@ -20,13 +20,13 @@
 import com.google.common.collect.ImmutableTable;
 import com.google.common.collect.Sets;
 import com.google.common.collect.Table;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 
 import java.util.Collection;
 import java.util.Collections;
@@ -209,7 +209,7 @@
         try {
           Label label = Label.parseAbsolute(str.substring("exception=".length()));
           exceptions.add(label);
-        } catch (SyntaxException e) {
+        } catch (LabelSyntaxException e) {
           throw new LicenseParsingException(e.getMessage());
         }
       } else {
diff --git a/src/main/java/com/google/devtools/build/lib/packages/Package.java b/src/main/java/com/google/devtools/build/lib/packages/Package.java
index 256aab0..0fbc726 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/Package.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/Package.java
@@ -24,6 +24,7 @@
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.collect.CollectionUtils;
 import com.google.devtools.build.lib.collect.ImmutableSortedKeyMap;
@@ -36,7 +37,6 @@
 import com.google.devtools.build.lib.packages.PackageFactory.Globber;
 import com.google.devtools.build.lib.syntax.FuncallExpression;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.util.Pair;
 import com.google.devtools.build.lib.vfs.Canonicalizer;
 import com.google.devtools.build.lib.vfs.Path;
@@ -586,7 +586,7 @@
       throw new NoSuchTargetException(createLabel(targetName), "target '" + targetName
           + "' not declared in package '" + name + "'" + suffix + " defined by "
           + this.filename);
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new IllegalArgumentException(targetName);
     }
   }
@@ -594,9 +594,9 @@
   /**
    * Creates a label for a target inside this package.
    *
-   * @throws SyntaxException if the {@code targetName} is invalid
+   * @throws LabelSyntaxException if the {@code targetName} is invalid
    */
-  public Label createLabel(String targetName) throws SyntaxException {
+  public Label createLabel(String targetName) throws LabelSyntaxException {
     return Label.create(packageIdentifier, targetName);
   }
 
@@ -841,7 +841,7 @@
       try {
         buildFileLabel = createLabel(filename.getBaseName());
         addInputFile(buildFileLabel, Location.fromFile(filename));
-      } catch (Label.SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         // This can't actually happen.
         throw new AssertionError("Package BUILD file has an illegal name: " + filename);
       }
@@ -1105,7 +1105,7 @@
       if (existing == null) {
         try {
           return addInputFile(createLabel(targetName), location);
-        } catch (Label.SyntaxException e) {
+        } catch (LabelSyntaxException e) {
           throw new IllegalArgumentException("FileTarget in package " + pkg.getName()
                                              + " has illegal name: " + targetName);
         }
@@ -1142,9 +1142,9 @@
     /**
      * Creates a label for a target inside this package.
      *
-     * @throws SyntaxException if the {@code targetName} is invalid
+     * @throws LabelSyntaxException if the {@code targetName} is invalid
      */
-    Label createLabel(String targetName) throws SyntaxException {
+    Label createLabel(String targetName) throws LabelSyntaxException {
       return Label.create(pkg.getPackageIdentifier(), targetName);
     }
 
@@ -1153,7 +1153,7 @@
      */
     void addPackageGroup(String name, Collection<String> packages, Collection<Label> includes,
         EventHandler eventHandler, Location location)
-        throws NameConflictException, Label.SyntaxException {
+        throws NameConflictException, LabelSyntaxException {
       PackageGroup group =
           new PackageGroup(createLabel(name), pkg, packages, includes, eventHandler, location);
       Target existing = targets.get(group.getName());
@@ -1190,7 +1190,7 @@
      */
     void addEnvironmentGroup(String name, List<Label> environments, List<Label> defaults,
         EventHandler eventHandler, Location location)
-        throws NameConflictException, SyntaxException {
+        throws NameConflictException, LabelSyntaxException {
 
       if (!checkForDuplicateLabels(environments, name, "environments", location, eventHandler)
           || !checkForDuplicateLabels(defaults, name, "defaults", location, eventHandler)) {
diff --git a/src/main/java/com/google/devtools/build/lib/packages/PackageDeserializer.java b/src/main/java/com/google/devtools/build/lib/packages/PackageDeserializer.java
index 2f0715c..9dbb7ef 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/PackageDeserializer.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/PackageDeserializer.java
@@ -23,8 +23,8 @@
 import com.google.common.collect.ImmutableList.Builder;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Sets;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
-import com.google.devtools.build.lib.cmdline.TargetParsingException;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.events.NullEventHandler;
@@ -40,7 +40,6 @@
 import com.google.devtools.build.lib.syntax.GlobCriteria;
 import com.google.devtools.build.lib.syntax.GlobList;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
 
@@ -92,7 +91,7 @@
               public Label load(String labelString) throws PackageDeserializationException {
                 try {
                   return Label.parseAbsolute(labelString);
-                } catch (SyntaxException e) {
+                } catch (LabelSyntaxException e) {
                   throw new PackageDeserializationException("Invalid label: " + e.getMessage(), e);
                 }
               }
@@ -160,7 +159,7 @@
           deserializeLabels(packageGroupPb.getIncludedPackageGroupList()),
           NullEventHandler.INSTANCE,  // TODO(bazel-team): Handle errors properly
           EmptyLocation.INSTANCE);
-    } catch (Label.SyntaxException | Package.NameConflictException e) {
+    } catch (LabelSyntaxException | Package.NameConflictException e) {
       throw new PackageDeserializationException(e);
     }
   }
@@ -183,7 +182,7 @@
       context.packageBuilder.addRule(rule);
 
       Preconditions.checkState(!rule.containsErrors());
-    } catch (NameConflictException | SyntaxException e) {
+    } catch (NameConflictException | LabelSyntaxException e) {
       throw new PackageDeserializationException(e);
     }
   }
@@ -452,7 +451,7 @@
       builder = new Package.Builder(
           new PackageIdentifier(packagePb.getRepository(), new PathFragment(packagePb.getName())),
           null);
-    } catch (TargetParsingException e) {
+    } catch (LabelSyntaxException e) {
       throw new PackageDeserializationException(e);
     }
     StoredEventHandler eventHandler = new StoredEventHandler();
diff --git a/src/main/java/com/google/devtools/build/lib/packages/PackageFactory.java b/src/main/java/com/google/devtools/build/lib/packages/PackageFactory.java
index 4fd5428..1a7c376 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/PackageFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/PackageFactory.java
@@ -21,6 +21,7 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.LabelValidator;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.events.Event;
@@ -626,7 +627,7 @@
                 context.pkgBuilder.addEnvironmentGroup(
                     name, environments, defaults, context.eventHandler, loc);
                 return Runtime.NONE;
-              } catch (Label.SyntaxException e) {
+              } catch (LabelSyntaxException e) {
                 throw new EvalException(loc,
                     "environment group has invalid name: " + name + ": " + e.getMessage());
               } catch (Package.NameConflictException e) {
@@ -819,7 +820,7 @@
       context.pkgBuilder.addPackageGroup(name, packages, includes, context.eventHandler,
           ast.getLocation());
       return Runtime.NONE;
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new EvalException(ast.getLocation(),
           "package group has invalid name: " + name + ": " + e.getMessage());
     } catch (Package.NameConflictException e) {
diff --git a/src/main/java/com/google/devtools/build/lib/packages/Rule.java b/src/main/java/com/google/devtools/build/lib/packages/Rule.java
index da1c804..4802169 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/Rule.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/Rule.java
@@ -27,6 +27,7 @@
 import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Multimap;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.events.Location;
@@ -36,7 +37,6 @@
 import com.google.devtools.build.lib.syntax.FuncallExpression;
 import com.google.devtools.build.lib.syntax.GlobList;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.util.BinaryPredicate;
 
 import java.util.Collection;
@@ -484,7 +484,7 @@
    * will retain the relative order in which they were declared.
    */
   void populateOutputFiles(EventHandler eventHandler, Package.Builder pkgBuilder)
-      throws SyntaxException, InterruptedException {
+      throws LabelSyntaxException, InterruptedException {
     Preconditions.checkState(outputFiles == null);
     // Order is important here: implicit before explicit
     outputFiles = Lists.newArrayList();
@@ -496,7 +496,7 @@
   }
 
   // Explicit output files are user-specified attributes of type OUTPUT.
-  private void populateExplicitOutputFiles(EventHandler eventHandler) throws SyntaxException {
+  private void populateExplicitOutputFiles(EventHandler eventHandler) throws LabelSyntaxException {
     NonconfigurableAttributeMapper nonConfigurableAttributes =
         NonconfigurableAttributeMapper.of(this);
     for (Attribute attribute : ruleClass.getAttributes()) {
@@ -525,7 +525,7 @@
       for (String out : ruleClass.getImplicitOutputsFunction().getImplicitOutputs(attributeMap)) {
         try {
           addOutputFile(pkgBuilder.createLabel(out), eventHandler);
-        } catch (SyntaxException e) {
+        } catch (LabelSyntaxException e) {
           reportError("illegal output file name '" + out + "' in rule "
                       + getLabel(), eventHandler);
         }
@@ -536,7 +536,7 @@
   }
 
   private void addLabelOutput(Attribute attribute, Label label, EventHandler eventHandler)
-      throws SyntaxException {
+      throws LabelSyntaxException {
     if (!label.getPackageIdentifier().equals(pkg.getPackageIdentifier())) {
       throw new IllegalStateException("Label for attribute " + attribute
           + " should refer to '" + pkg.getName()
@@ -544,7 +544,7 @@
           + "' (label '" + label.getName() + "')");
     }
     if (label.getName().equals(".")) {
-      throw new SyntaxException("output file name can't be equal '.'");
+      throw new LabelSyntaxException("output file name can't be equal '.'");
     }
     OutputFile outputFile = addOutputFile(label, eventHandler);
     outputFileMap.put(attribute.getName(), outputFile);
diff --git a/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java b/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
index 1e7dd2a..34ff1af 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
@@ -29,6 +29,7 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Ordering;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition;
@@ -40,7 +41,6 @@
 import com.google.devtools.build.lib.syntax.FuncallExpression;
 import com.google.devtools.build.lib.syntax.GlobList;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.syntax.Runtime;
 import com.google.devtools.build.lib.util.StringUtil;
 import com.google.devtools.build.lib.vfs.PathFragment;
@@ -1315,7 +1315,7 @@
    */
   Rule createRuleWithLabel(Package.Builder pkgBuilder, Label ruleLabel,
       Map<String, Object> attributeValues, EventHandler eventHandler, FuncallExpression ast,
-      Location location) throws SyntaxException, InterruptedException {
+      Location location) throws LabelSyntaxException, InterruptedException {
     Rule rule = pkgBuilder.newRuleWithLabel(ruleLabel, this, null, location);
     createRuleCommon(rule, pkgBuilder, attributeValues, eventHandler, ast);
     return rule;
@@ -1323,7 +1323,7 @@
 
   private void createRuleCommon(Rule rule, Package.Builder pkgBuilder,
       Map<String, Object> attributeValues, EventHandler eventHandler, FuncallExpression ast)
-      throws SyntaxException, InterruptedException {
+      throws LabelSyntaxException, InterruptedException {
     populateRuleAttributeValues(
         rule, pkgBuilder, attributeValues, eventHandler, ast);
     rule.populateOutputFiles(eventHandler, pkgBuilder);
@@ -1365,7 +1365,7 @@
   Rule createRuleWithParsedAttributeValues(Label label,
       Package.Builder pkgBuilder, Location ruleLocation,
       Map<String, ParsedAttributeValue> attributeValues, EventHandler eventHandler)
-          throws SyntaxException, InterruptedException {
+          throws LabelSyntaxException, InterruptedException {
     Rule rule = pkgBuilder.newRuleWithLabel(label, this, null, ruleLocation);
     rule.checkValidityPredicate(eventHandler);
 
diff --git a/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java b/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java
index f647c07..1eb2834 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java
@@ -16,6 +16,7 @@
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.packages.Package.NameConflictException;
@@ -24,7 +25,6 @@
 import com.google.devtools.build.lib.syntax.Environment;
 import com.google.devtools.build.lib.syntax.FuncallExpression;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.syntax.UserDefinedFunction;
 import com.google.devtools.build.lib.util.Pair;
 
@@ -98,7 +98,7 @@
       // Test that this would form a valid label name -- in particular, this
       // catches cases where Makefile variables $(foo) appear in "name".
       label = pkgBuilder.createLabel(name);
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new InvalidRuleException("illegal rule name: " + name + ": " + e.getMessage());
     }
     boolean inWorkspaceFile =
@@ -115,7 +115,7 @@
     try {
       return ruleClass.createRuleWithLabel(
           pkgBuilder, label, generator.attributes, eventHandler, ast, generator.location);
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new RuleFactory.InvalidRuleException(ruleClass + " " + e.getMessage());
     }
   }
diff --git a/src/main/java/com/google/devtools/build/lib/packages/Type.java b/src/main/java/com/google/devtools/build/lib/packages/Type.java
index b88c7a1..fa2ce67 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/Type.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/Type.java
@@ -23,6 +23,7 @@
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.packages.License.DistributionType;
 import com.google.devtools.build.lib.packages.License.LicenseParsingException;
 import com.google.devtools.build.lib.syntax.EvalException;
@@ -670,7 +671,7 @@
       try {
         return currentRule.getRelative(
             STRING.convert(x, what, currentRule));
-      } catch (Label.SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         throw new ConversionException("invalid label '" + x + "' in "
             + what + ": " + e.getMessage());
       }
@@ -796,7 +797,7 @@
           throw new ConversionException("label '" + value + "' is not in the current package");
         }
         return result;
-      } catch (Label.SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         throw new ConversionException(
             "illegal output file name '" + value + "' in rule " + currentRule + ": "
             + e.getMessage());
@@ -1043,7 +1044,7 @@
 
       try {
         defaultConditionLabel = Label.parseAbsolute(DEFAULT_CONDITION_KEY);
-      } catch (Label.SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         throw new IllegalStateException(DEFAULT_CONDITION_KEY + " is not a valid label");
       }
 
diff --git a/src/main/java/com/google/devtools/build/lib/packages/WorkspaceFactory.java b/src/main/java/com/google/devtools/build/lib/packages/WorkspaceFactory.java
index 74def59..a19b36b 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/WorkspaceFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/WorkspaceFactory.java
@@ -16,6 +16,7 @@
 
 import static com.google.devtools.build.lib.syntax.Runtime.NONE;
 
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.LabelValidator;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.Location;
@@ -119,11 +120,11 @@
             builder.addBindRule(ruleClass, nameLabel,
                 actual == null ? null : Label.parseAbsolute(actual), loc);
           } catch (RuleFactory.InvalidRuleException | Package.NameConflictException |
-            Label.SyntaxException e) {
+              LabelSyntaxException e) {
             throw new EvalException(loc, e.getMessage());
           }
 
-        } catch (Label.SyntaxException e) {
+        } catch (LabelSyntaxException e) {
           throw new EvalException(loc, e.getMessage());
         }
         return NONE;
@@ -146,7 +147,7 @@
           RuleClass bindRuleClass = ruleFactory.getRuleClass("bind");
           builder.createAndAddRepositoryRule(ruleClass, bindRuleClass, kwargs, ast, env);
         } catch (RuleFactory.InvalidRuleException | Package.NameConflictException |
-            Label.SyntaxException e) {
+            LabelSyntaxException e) {
           throw new EvalException(ast.getLocation(), e.getMessage());
         }
         return NONE;
diff --git a/src/main/java/com/google/devtools/build/lib/pkgcache/TargetPatternResolverUtil.java b/src/main/java/com/google/devtools/build/lib/pkgcache/TargetPatternResolverUtil.java
index a291150..c1794c0 100644
--- a/src/main/java/com/google/devtools/build/lib/pkgcache/TargetPatternResolverUtil.java
+++ b/src/main/java/com/google/devtools/build/lib/pkgcache/TargetPatternResolverUtil.java
@@ -14,6 +14,7 @@
 package com.google.devtools.build.lib.pkgcache;
 
 import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.LabelValidator;
 import com.google.devtools.build.lib.cmdline.ResolvedTargets;
 import com.google.devtools.build.lib.cmdline.TargetParsingException;
@@ -32,12 +33,12 @@
     // Utility class.
   }
 
-  // Parse 'label' as a Label, mapping Label.SyntaxException into
+  // Parse 'label' as a Label, mapping LabelSyntaxException into
   // TargetParsingException.
   public static Label label(String label) throws TargetParsingException {
     try {
       return Label.parseAbsolute(label);
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw invalidTarget(label, e.getMessage());
     }
   }
diff --git a/src/main/java/com/google/devtools/build/lib/query2/BlazeQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/BlazeQueryEnvironment.java
index da7c3d9..24cc3f2 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/BlazeQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/BlazeQueryEnvironment.java
@@ -19,6 +19,7 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Maps;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.ResolvedTargets;
 import com.google.devtools.build.lib.cmdline.TargetParsingException;
 import com.google.devtools.build.lib.events.EventHandler;
@@ -339,7 +340,7 @@
           try {
             addIfUniqueLabel(getSubincludeTarget(
                 subinclude.getLocalTargetLabel("BUILD"), pkg), seenLabels, dependentFiles);
-          } catch (Label.SyntaxException e) {
+          } catch (LabelSyntaxException e) {
             throw new AssertionError("BUILD should always parse as a target name", e);
           }
         }
diff --git a/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
index 1945c45..6171081 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
@@ -26,6 +26,7 @@
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Multimap;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.cmdline.TargetParsingException;
 import com.google.devtools.build.lib.cmdline.TargetPattern;
@@ -327,7 +328,7 @@
           try {
             addIfUniqueLabel(getSubincludeTarget(
                 subinclude.getLocalTargetLabel("BUILD"), pkg), seenLabels, dependentFiles);
-          } catch (Label.SyntaxException e) {
+          } catch (LabelSyntaxException e) {
             throw new AssertionError("BUILD should always parse as a target name", e);
           }
         }
diff --git a/src/main/java/com/google/devtools/build/lib/query2/output/PreciseAspectResolver.java b/src/main/java/com/google/devtools/build/lib/query2/output/PreciseAspectResolver.java
index dee20c4..a9c9936 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/output/PreciseAspectResolver.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/output/PreciseAspectResolver.java
@@ -16,6 +16,7 @@
 import com.google.common.collect.ImmutableMultimap;
 import com.google.common.collect.LinkedListMultimap;
 import com.google.common.collect.Multimap;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.packages.AspectDefinition;
@@ -119,7 +120,7 @@
         // If the package is not found, just add its BUILD file, which is already done above.
         // Hopefully this error is not raised when there is a syntax error in a subincluded file
         // or something.
-      } catch (Label.SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         throw new IllegalStateException(e);
       }
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleClassFunctions.java b/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleClassFunctions.java
index 2595cf9..066ac52 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleClassFunctions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleClassFunctions.java
@@ -38,6 +38,7 @@
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.config.RunUnder;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition;
@@ -115,7 +116,7 @@
     public Label load(String from) throws Exception {
       try {
         return Label.parseAbsolute(from);
-      } catch (Label.SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         throw new Exception(from);
       }
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
index c999e7f..1b9f786 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
@@ -38,13 +38,13 @@
 import com.google.devtools.build.lib.analysis.config.CompilationMode;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
 import com.google.devtools.build.lib.analysis.config.PerLabelOptions;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.rules.cpp.CppConfigurationLoader.CppConfigurationParameters;
 import com.google.devtools.build.lib.rules.cpp.FdoSupport.FdoException;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.syntax.SkylarkCallable;
 import com.google.devtools.build.lib.syntax.SkylarkModule;
 import com.google.devtools.build.lib.util.IncludeScanningUtil;
@@ -382,7 +382,7 @@
       this.dynamicRuntimeLibsLabel =
           crosstoolTop.getRelative(toolchain.hasDynamicRuntimesFilegroup() ?
               toolchain.getDynamicRuntimesFilegroup() : "dynamic-runtime-libs-" + targetCpu);
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       // All of the above label.getRelative() calls are valid labels, and the crosstool_top
       // was already checked earlier in the process.
       throw new AssertionError(e);
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfigurationLoader.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfigurationLoader.java
index 2ad010a..96b1add 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfigurationLoader.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfigurationLoader.java
@@ -25,6 +25,7 @@
 import com.google.devtools.build.lib.analysis.config.ConfigurationFragmentFactory;
 import com.google.devtools.build.lib.analysis.config.FragmentOptions;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.packages.InputFile;
 import com.google.devtools.build.lib.packages.NoSuchPackageException;
 import com.google.devtools.build.lib.packages.NoSuchTargetException;
@@ -34,7 +35,6 @@
 import com.google.devtools.build.lib.packages.Target;
 import com.google.devtools.build.lib.packages.Type;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.view.config.crosstool.CrosstoolConfig;
@@ -153,7 +153,7 @@
           throw new InvalidConfigurationException(
               "The --fdo_optimize parameter you specified resolves to a file that does not exist");
         }
-      } catch (NoSuchPackageException | NoSuchTargetException | SyntaxException e) {
+      } catch (NoSuchPackageException | NoSuchTargetException | LabelSyntaxException e) {
         throw new InvalidConfigurationException(e);
       }
     } else {
@@ -189,7 +189,7 @@
     } else {
       try {
         ccToolchainLabel = crosstoolTopLabel.getRelative("cc-compiler-" + toolchain.getTargetCpu());
-      } catch (Label.SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         throw new InvalidConfigurationException(String.format(
             "'%s' is not a valid CPU. It should only consist of characters valid in labels",
             toolchain.getTargetCpu()));
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppHelper.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppHelper.java
index 0a628f3..1e8b247 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppHelper.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppHelper.java
@@ -30,6 +30,7 @@
 import com.google.devtools.build.lib.analysis.TransitiveInfoCollection;
 import com.google.devtools.build.lib.analysis.actions.SpawnAction;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.packages.RuleErrorConsumer;
 import com.google.devtools.build.lib.packages.Type;
@@ -38,7 +39,6 @@
 import com.google.devtools.build.lib.rules.cpp.Link.LinkTargetType;
 import com.google.devtools.build.lib.shell.ShellUtils;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.util.FileTypeSet;
 import com.google.devtools.build.lib.util.IncludeScanningUtil;
 import com.google.devtools.build.lib.vfs.PathFragment;
@@ -198,7 +198,7 @@
           return true;
         }
       }
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       // Quietly ignore and fall through.
     }
     linkopts.add(labelName);
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java
index 7915bb2..ebb4e77 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java
@@ -24,11 +24,11 @@
 import com.google.devtools.build.lib.analysis.config.CompilationMode;
 import com.google.devtools.build.lib.analysis.config.FragmentOptions;
 import com.google.devtools.build.lib.analysis.config.PerLabelOptions;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.rules.cpp.CppConfiguration.HeadersCheckingMode;
 import com.google.devtools.build.lib.rules.cpp.CppConfiguration.LibcTop;
 import com.google.devtools.build.lib.rules.cpp.CppConfiguration.StripMode;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.util.OptionsUtils;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import com.google.devtools.build.lib.view.config.crosstool.CrosstoolConfig.LipoMode;
@@ -134,7 +134,7 @@
       try {
         Label label = Label.parseAbsolute(input).getRelative(LIBC_RELATIVE_LABEL);
         return new LibcTop(label);
-      } catch (SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         throw new OptionsParsingException(e.getMessage());
       }
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CrosstoolConfigurationLoader.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CrosstoolConfigurationLoader.java
index 15e91e2..22ae3ec 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CrosstoolConfigurationLoader.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CrosstoolConfigurationLoader.java
@@ -25,6 +25,7 @@
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.analysis.config.ConfigurationEnvironment;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.packages.NoSuchThingException;
 import com.google.devtools.build.lib.packages.NonconfigurableAttributeMapper;
 import com.google.devtools.build.lib.packages.Package;
@@ -32,7 +33,6 @@
 import com.google.devtools.build.lib.packages.Target;
 import com.google.devtools.build.lib.packages.Type;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.util.Fingerprint;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.Path;
@@ -210,7 +210,7 @@
         return null;
       }
       path = env.getPath(containingPackage, CROSSTOOL_CONFIGURATION_FILENAME);
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new InvalidConfigurationException(e);
     } catch (NoSuchThingException e) {
       // Handled later
diff --git a/src/main/java/com/google/devtools/build/lib/rules/genquery/GenQuery.java b/src/main/java/com/google/devtools/build/lib/rules/genquery/GenQuery.java
index 737ab6d..dfe8715 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/genquery/GenQuery.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/genquery/GenQuery.java
@@ -183,7 +183,7 @@
     for (Label scopePart : scopeLabels) {
       SkyFunction.Environment env = context.getAnalysisEnvironment().getSkyframeEnv();
       PackageValue packageNode =
-          (PackageValue) env.getValue(PackageValue.key(scopePart.getPackageFragment()));
+          (PackageValue) env.getValue(PackageValue.key(scopePart.getPackageIdentifier()));
       Preconditions.checkNotNull(
           packageNode,
           "Packages in transitive closure of scope '%s'"
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaConfiguration.java
index 2151bff..ffca843 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaConfiguration.java
@@ -19,11 +19,11 @@
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration.StrictDepsMode;
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.syntax.SkylarkCallable;
 import com.google.devtools.build.lib.syntax.SkylarkModule;
 import com.google.devtools.common.options.TriState;
@@ -97,7 +97,7 @@
       try {
         Label label = Label.parseAbsolute(s);
         translationsBuilder.add(label);
-      } catch (SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         throw new InvalidConfigurationException("Invalid translations target '" + s + "', make " +
             "sure it uses correct absolute path syntax.", e);
       }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaOptions.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaOptions.java
index 4b564a5..6b7a353 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaOptions.java
@@ -22,9 +22,9 @@
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration.StrictDepsMode;
 import com.google.devtools.build.lib.analysis.config.DefaultsPackage;
 import com.google.devtools.build.lib.analysis.config.FragmentOptions;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.rules.java.JavaConfiguration.JavaClasspathMode;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.common.options.Converters.StringSetConverter;
 import com.google.devtools.common.options.EnumConverter;
 import com.google.devtools.common.options.Option;
@@ -362,7 +362,7 @@
       try {
         Label label = Label.parseAbsolute(s);
         result.add(label);
-      } catch (SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         // We ignore this exception here - it will cause an error message at a later time.
       }
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JvmConfigurationLoader.java b/src/main/java/com/google/devtools/build/lib/rules/java/JvmConfigurationLoader.java
index c6fff96..ecc013a 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JvmConfigurationLoader.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JvmConfigurationLoader.java
@@ -23,6 +23,7 @@
 import com.google.devtools.build.lib.analysis.config.ConfigurationFragmentFactory;
 import com.google.devtools.build.lib.analysis.config.FragmentOptions;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.packages.NoSuchPackageException;
 import com.google.devtools.build.lib.packages.NoSuchTargetException;
 import com.google.devtools.build.lib.packages.RawAttributeMapper;
@@ -30,7 +31,6 @@
 import com.google.devtools.build.lib.packages.Target;
 import com.google.devtools.build.lib.packages.Type;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.vfs.PathFragment;
 
 import java.util.List;
@@ -156,7 +156,7 @@
       throw new InvalidConfigurationException(e.getMessage(), e);
     } catch (NoSuchTargetException e) {
       throw new InvalidConfigurationException("No such target: " + e.getMessage(), e);
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new InvalidConfigurationException(e.getMessage(), e);
     }
   }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java
index 130be53..1570d7f 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java
@@ -32,6 +32,7 @@
 import com.google.devtools.build.lib.analysis.actions.CustomCommandLine;
 import com.google.devtools.build.lib.analysis.actions.ParameterFileWriteAction;
 import com.google.devtools.build.lib.analysis.actions.SpawnAction;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.packages.AspectDefinition;
@@ -44,7 +45,6 @@
 import com.google.devtools.build.lib.rules.java.Jvm;
 import com.google.devtools.build.lib.rules.objc.J2ObjcSource.SourceType;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.util.FileType;
 import com.google.devtools.build.lib.vfs.PathFragment;
 
@@ -83,7 +83,7 @@
   private static Label parseLabel(String from) {
     try {
       return Label.parseAbsolute(from);
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new IllegalArgumentException(from);
     }
   }
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ConfigurationFragmentFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ConfigurationFragmentFunction.java
index d19da4b..b48c027 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ConfigurationFragmentFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ConfigurationFragmentFunction.java
@@ -22,13 +22,13 @@
 import com.google.devtools.build.lib.analysis.config.ConfigurationFragmentFactory;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
 import com.google.devtools.build.lib.analysis.config.PackageProviderForConfigurations;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.packages.NoSuchPackageException;
 import com.google.devtools.build.lib.packages.NoSuchTargetException;
 import com.google.devtools.build.lib.packages.Package;
 import com.google.devtools.build.lib.packages.Target;
 import com.google.devtools.build.lib.skyframe.ConfigurationFragmentValue.ConfigurationFragmentKey;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.skyframe.SkyFunction;
 import com.google.devtools.build.skyframe.SkyFunctionException;
@@ -112,7 +112,7 @@
       Path result = pkg.getPackageDirectory().getRelative(fileName);
       try {
         loadedPackageProvider.addDependency(pkg, fileName);
-      } catch (IOException | SyntaxException e) {
+      } catch (IOException | LabelSyntaxException e) {
         return null;
       }
       return result;
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java
index cf0bf4e..95fef27 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java
@@ -378,11 +378,11 @@
       }
     }
 
-    if (packageName.equals(EXTERNAL_PACKAGE_NAME)) {
+    if (packageId.equals(ExternalPackage.PACKAGE_IDENTIFIER)) {
       return getExternalPackage(env, packageLookupValue.getRoot());
     }
     PackageValue externalPackage = (PackageValue) env.getValue(
-        PackageValue.key(PackageIdentifier.createInDefaultRepo(EXTERNAL_PACKAGE_NAME)));
+        PackageValue.key(ExternalPackage.PACKAGE_IDENTIFIER));
     if (externalPackage == null) {
       return null;
     }
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java
index ad815e1..610971d 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java
@@ -51,9 +51,10 @@
   public SkyValue compute(SkyKey skyKey, Environment env) throws PackageLookupFunctionException {
     PathPackageLocator pkgLocator = PrecomputedValue.PATH_PACKAGE_LOCATOR.get(env);
     PackageIdentifier packageKey = (PackageIdentifier) skyKey.argument();
-    if (!packageKey.getRepository().isDefault()) {
+    if (!packageKey.getRepository().equals(PackageIdentifier.MAIN_REPOSITORY_NAME)
+        && !packageKey.getRepository().isDefault()) {
       return computeExternalPackageLookupValue(skyKey, env, packageKey);
-    } else if (packageKey.getPackageFragment().equals(new PathFragment(ExternalPackage.NAME))) {
+    } else if (packageKey.equals(ExternalPackage.PACKAGE_IDENTIFIER)) {
       return computeWorkspaceLookupValue(env, packageKey);
     }
 
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PackageValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/PackageValue.java
index f90df2d..ade85a7 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/PackageValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PackageValue.java
@@ -18,7 +18,6 @@
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
 import com.google.devtools.build.lib.packages.Package;
-import com.google.devtools.build.lib.vfs.PathFragment;
 import com.google.devtools.build.lib.vfs.RootedPath;
 import com.google.devtools.build.skyframe.SkyKey;
 import com.google.devtools.build.skyframe.SkyValue;
@@ -45,11 +44,6 @@
     return "<PackageValue name=" + pkg.getName() + ">";
   }
 
-  @ThreadSafe
-  public static SkyKey key(PathFragment pkgName) {
-    return key(PackageIdentifier.createInDefaultRepo(pkgName));
-  }
-
   public static SkyKey key(PackageIdentifier pkgIdentifier) {
     return new SkyKey(SkyFunctions.PACKAGE, pkgIdentifier);
   }
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/RecursivePackageProviderBackedTargetPatternResolver.java b/src/main/java/com/google/devtools/build/lib/skyframe/RecursivePackageProviderBackedTargetPatternResolver.java
index 891a39c..051215d 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/RecursivePackageProviderBackedTargetPatternResolver.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/RecursivePackageProviderBackedTargetPatternResolver.java
@@ -14,6 +14,7 @@
 package com.google.devtools.build.lib.skyframe;
 
 import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.cmdline.ResolvedTargets;
 import com.google.devtools.build.lib.cmdline.TargetParsingException;
@@ -87,7 +88,7 @@
         return null;
       }
       return recursivePackageProvider.getTarget(eventHandler, label);
-    } catch (Label.SyntaxException | NoSuchThingException e) {
+    } catch (LabelSyntaxException | NoSuchThingException e) {
       return null;
     }
   }
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframePackageLoaderWithValueEnvironment.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframePackageLoaderWithValueEnvironment.java
index 64ee756..80ccb13 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframePackageLoaderWithValueEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframePackageLoaderWithValueEnvironment.java
@@ -18,6 +18,7 @@
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
 import com.google.devtools.build.lib.analysis.config.PackageProviderForConfigurations;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.packages.NoSuchPackageException;
 import com.google.devtools.build.lib.packages.NoSuchTargetException;
@@ -25,7 +26,6 @@
 import com.google.devtools.build.lib.packages.Target;
 import com.google.devtools.build.lib.skyframe.SkyframeExecutor.SkyframePackageLoader;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.vfs.RootedPath;
 import com.google.devtools.build.skyframe.MemoizingEvaluator;
 import com.google.devtools.build.skyframe.SkyFunction;
@@ -81,7 +81,7 @@
   }
 
   @Override
-  public void addDependency(Package pkg, String fileName) throws SyntaxException, IOException {
+  public void addDependency(Package pkg, String fileName) throws LabelSyntaxException, IOException {
     RootedPath fileRootedPath = RootedPath.toRootedPath(pkg.getSourceRoot(),
         pkg.getNameFragment().getRelative(fileName));
     FileValue result = (FileValue) env.getValue(FileValue.key(fileRootedPath));
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkylarkImportLookupFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkylarkImportLookupFunction.java
index bcf56c4..d5c6b39 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkylarkImportLookupFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkylarkImportLookupFunction.java
@@ -14,6 +14,7 @@
 package com.google.devtools.build.lib.skyframe;
 
 import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier.RepositoryName;
 import com.google.devtools.build.lib.events.Event;
@@ -27,7 +28,6 @@
 import com.google.devtools.build.lib.syntax.BuildFileAST;
 import com.google.devtools.build.lib.syntax.Environment.Extension;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.syntax.Mutability;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import com.google.devtools.build.skyframe.SkyFunction;
@@ -160,7 +160,7 @@
     try {
       // This code relies on PackageIdentifier.RepositoryName.toString()
       return Label.parseAbsolute(repo + "//" + pkgName.getPathString() + ":" + fileInPkg);
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new IllegalStateException(e);
     }
   }
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/TargetPatternValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/TargetPatternValue.java
index 1f665e0..c91d279 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/TargetPatternValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/TargetPatternValue.java
@@ -17,6 +17,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.ResolvedTargets;
 import com.google.devtools.build.lib.cmdline.ResolvedTargets.Builder;
 import com.google.devtools.build.lib.cmdline.TargetParsingException;
@@ -26,7 +27,6 @@
 import com.google.devtools.build.lib.pkgcache.FilteringPolicies;
 import com.google.devtools.build.lib.pkgcache.FilteringPolicy;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.skyframe.SkyKey;
 import com.google.devtools.build.skyframe.SkyValue;
 
@@ -69,7 +69,7 @@
   private Label labelFromString(String labelString) {
     try {
       return Label.parseAbsolute(labelString);
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new IllegalStateException(e);
     }
   }
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/BuildFileAST.java b/src/main/java/com/google/devtools/build/lib/syntax/BuildFileAST.java
index cdd75d3..bbaf3b0 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/BuildFileAST.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/BuildFileAST.java
@@ -17,6 +17,7 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.hash.HashCode;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.events.Location;
@@ -97,7 +98,7 @@
       try {
         Label label = Label.parseAbsolute(((StringLiteral) arg).getValue());
         result.add(label);
-      } catch (Label.SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         // Ignore. This will be reported when the BUILD file is actually evaluated.
       }
     }
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/CommaSeparatedPackageNameListConverter.java b/src/main/java/com/google/devtools/build/lib/syntax/CommaSeparatedPackageNameListConverter.java
index 5d5c598..78faf36 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/CommaSeparatedPackageNameListConverter.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/CommaSeparatedPackageNameListConverter.java
@@ -16,8 +16,8 @@
 import com.google.common.base.Splitter;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
-import com.google.devtools.build.lib.cmdline.TargetParsingException;
 import com.google.devtools.common.options.Converter;
 import com.google.devtools.common.options.OptionsParsingException;
 
@@ -40,7 +40,7 @@
     for (String s : SPACE_SPLITTER.split(input)) {
       try {
         list.add(PackageIdentifier.parse(s));
-      } catch (TargetParsingException e) {
+      } catch (LabelSyntaxException e) {
         throw new OptionsParsingException(e.getMessage());
       }
     }
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Label.java b/src/main/java/com/google/devtools/build/lib/syntax/Label.java
index c7994d9..6c712c3 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Label.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Label.java
@@ -15,10 +15,10 @@
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ComparisonChain;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.LabelValidator;
 import com.google.devtools.build.lib.cmdline.LabelValidator.BadLabelException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
-import com.google.devtools.build.lib.cmdline.TargetParsingException;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
 import com.google.devtools.build.lib.util.StringCanonicalizer;
@@ -42,15 +42,6 @@
 public final class Label implements Comparable<Label>, Serializable {
 
   /**
-   * Thrown by the parsing methods to indicate a bad label.
-   */
-  public static class SyntaxException extends Exception {
-    public SyntaxException(String message) {
-      super(message);
-    }
-  }
-
-  /**
    * Factory for Labels from absolute string form. e.g.
    * <pre>
    * //foo/bar
@@ -59,7 +50,7 @@
    * {@literal @}foo//bar:baz
    * </pre>
    */
-  public static Label parseAbsolute(String absName) throws SyntaxException {
+  public static Label parseAbsolute(String absName) throws LabelSyntaxException {
     String repo = PackageIdentifier.DEFAULT_REPOSITORY;
     int packageStartPos = absName.indexOf("//");
     if (packageStartPos > 0) {
@@ -71,8 +62,8 @@
       validate(labelParts.getPackageName(), labelParts.getTargetName());
       return new Label(new PackageIdentifier(repo, new PathFragment(labelParts.getPackageName())),
           labelParts.getTargetName());
-    } catch (BadLabelException | TargetParsingException e) {
-      throw new SyntaxException(e.getMessage());
+    } catch (BadLabelException e) {
+      throw new LabelSyntaxException(e.getMessage());
     }
   }
 
@@ -86,7 +77,7 @@
   public static Label parseAbsoluteUnchecked(String absName) {
     try {
       return parseAbsolute(absName);
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new IllegalArgumentException(e);
     }
   }
@@ -99,9 +90,9 @@
    *   {@link LabelValidator#validatePackageName}.
    * @param targetName The name of the target within the package.  Must be
    *   valid according to {@link LabelValidator#validateTargetName}.
-   * @throws SyntaxException if either of the arguments was invalid.
+   * @throws LabelSyntaxException if either of the arguments was invalid.
    */
-  public static Label create(String packageName, String targetName) throws SyntaxException {
+  public static Label create(String packageName, String targetName) throws LabelSyntaxException {
     return new Label(packageName, targetName);
   }
 
@@ -110,7 +101,7 @@
    * to be created.
    */
   public static Label create(PackageIdentifier packageId, String targetName)
-      throws SyntaxException {
+      throws LabelSyntaxException {
     return new Label(packageId, targetName);
   }
 
@@ -131,10 +122,10 @@
    * possible, because it is sometimes necessary to resolve a relative label before the package path
    * is setup; in particular, before the tools/defaults package is created.
    *
-   * @throws SyntaxException if the resulting label is not valid
+   * @throws LabelSyntaxException if the resulting label is not valid
    */
   public static Label parseCommandLineLabel(String label, PathFragment workspaceRelativePath)
-      throws SyntaxException {
+      throws LabelSyntaxException {
     Preconditions.checkArgument(!workspaceRelativePath.isAbsolute());
     if (LabelValidator.isAbsolute(label)) {
       return parseAbsolute(label);
@@ -154,11 +145,11 @@
    * Validates the given target name and returns a canonical String instance if it is valid.
    * Otherwise it throws a SyntaxException.
    */
-  private static String canonicalizeTargetName(String name) throws SyntaxException {
+  private static String canonicalizeTargetName(String name) throws LabelSyntaxException {
     String error = LabelValidator.validateTargetName(name);
     if (error != null) {
       error = "invalid target name '" + StringUtilities.sanitizeControlChars(name) + "': " + error;
-      throw new SyntaxException(error);
+      throw new LabelSyntaxException(error);
     }
 
     // TODO(bazel-team): This should be an error, but we can't make it one for legacy reasons.
@@ -173,19 +164,22 @@
    * Validates the given package name and returns a canonical PathFragment instance if it is valid.
    * Otherwise it throws a SyntaxException.
    */
-  private static PathFragment validate(String packageName, String name) throws SyntaxException {
-    String error = LabelValidator.validatePackageName(packageName);
-    if (error != null) {
-      error = "invalid package name '" + packageName + "': " + error;
+  private static PackageIdentifier validate(String packageIdentifier, String name)
+      throws LabelSyntaxException {
+    String error = null;
+    try {
+      return PackageIdentifier.parse(packageIdentifier);
+    } catch (LabelSyntaxException e) {
+      error = e.getMessage();
+      error = "invalid package name '" + packageIdentifier + "': " + error;
       // This check is just for a more helpful error message
       // i.e. valid target name, invalid package name, colon-free label form
       // used => probably they meant "//foo:bar.c" not "//foo/bar.c".
-      if (packageName.endsWith("/" + name)) {
+      if (packageIdentifier.endsWith("/" + name)) {
         error += " (perhaps you meant \":" + name + "\"?)";
       }
-      throw new SyntaxException(error);
+      throw new LabelSyntaxException(error);
     }
-    return new PathFragment(packageName);
   }
 
   /** The name and repository of the package. */
@@ -201,32 +195,24 @@
    * bazillion tests that use invalid package names (taking advantage of the fact that calling
    * Label(PathFragment, String) doesn't validate the package name).
    */
-  private Label(String packageName, String name) throws SyntaxException {
-    this(validate(packageName, name), name);
-  }
-
-  /**
-   * Constructor from canonical valid package name and a target name. The target
-   * name is checked for validity and a SyntaxException is throw if it isn't.
-   */
-  private Label(PathFragment packageName, String name) throws SyntaxException {
-    this(PackageIdentifier.createInDefaultRepo(packageName), name);
+  private Label(String packageIdentifier, String name) throws LabelSyntaxException {
+    this(validate(packageIdentifier, name), name);
   }
 
   private Label(PackageIdentifier packageIdentifier, String name)
-      throws SyntaxException {
+      throws LabelSyntaxException {
     Preconditions.checkNotNull(packageIdentifier);
     Preconditions.checkNotNull(name);
 
     try {
       this.packageIdentifier = packageIdentifier;
       this.name = canonicalizeTargetName(name);
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       // This check is just for a more helpful error message
       // i.e. valid target name, invalid package name, colon-free label form
       // used => probably they meant "//foo:bar.c" not "//foo/bar.c".
       if (packageIdentifier.getPackageFragment().getPathString().endsWith("/" + name)) {
-        throw new SyntaxException(e.getMessage() + " (perhaps you meant \":" + name + "\"?)");
+        throw new LabelSyntaxException(e.getMessage() + " (perhaps you meant \":" + name + "\"?)");
       }
       throw e;
     }
@@ -317,9 +303,9 @@
   /**
    * Returns a label in the same package as this label with the given target name.
    *
-   * @throws SyntaxException if {@code targetName} is not a valid target name
+   * @throws LabelSyntaxException if {@code targetName} is not a valid target name
    */
-  public Label getLocalTargetLabel(String targetName) throws SyntaxException {
+  public Label getLocalTargetLabel(String targetName) throws LabelSyntaxException {
     return new Label(packageIdentifier, targetName);
   }
 
@@ -341,14 +327,14 @@
       + "Label(\"//foo/bar:baz\").relative(\":quux\") == Label(\"//foo/bar:quux\")\n"
       + "Label(\"//foo/bar:baz\").relative(\"//wiz:quux\") == Label(\"//wiz:quux\")\n"
       + "</pre>")
-  public Label getRelative(String relName) throws SyntaxException {
+  public Label getRelative(String relName) throws LabelSyntaxException {
     if (relName.length() == 0) {
-      throw new SyntaxException("empty package-relative label");
+      throw new LabelSyntaxException("empty package-relative label");
     }
     if (LabelValidator.isAbsolute(relName)) {
       return parseAbsolute(relName);
     } else if (relName.equals(":")) {
-      throw new SyntaxException("':' is not a valid package-relative label");
+      throw new LabelSyntaxException("':' is not a valid package-relative label");
     } else if (relName.charAt(0) == ':') {
       return getLocalTargetLabel(relName.substring(1));
     } else {
@@ -372,7 +358,7 @@
         return new Label(
             new PackageIdentifier(packageIdentifier.getRepository(), relative.getPackageFragment()),
             relative.getName());
-      } catch (Label.SyntaxException e) {
+      } catch (LabelSyntaxException e) {
         // We are creating the new label from an existing one which is guaranteed to be valid, so
         // this can't happen
         throw new IllegalStateException(e);
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Parser.java b/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
index 97b04e6..2734e4f 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Parser.java
@@ -23,6 +23,7 @@
 import com.google.common.base.Supplier;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.events.Location;
@@ -646,7 +647,7 @@
       Parser parser = new Parser(lexer, eventHandler, locator, parsingMode);
       parser.addIncludedFiles(this.includedFiles);
       list.addAll(parser.parseFileInput());
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       reportError(location, "Invalid label '" + labelName + "'");
     } catch (IOException e) {
       reportError(location, "Include of '" + labelName + "' failed: " + e.getMessage());
diff --git a/src/test/java/com/google/devtools/build/lib/actions/CustomCommandLineTest.java b/src/test/java/com/google/devtools/build/lib/actions/CustomCommandLineTest.java
index 3a7db34..c5e1eaf 100644
--- a/src/test/java/com/google/devtools/build/lib/actions/CustomCommandLineTest.java
+++ b/src/test/java/com/google/devtools/build/lib/actions/CustomCommandLineTest.java
@@ -20,9 +20,9 @@
 import com.google.devtools.build.lib.analysis.actions.CustomCommandLine;
 import com.google.devtools.build.lib.analysis.actions.CustomCommandLine.CustomArgv;
 import com.google.devtools.build.lib.analysis.actions.CustomCommandLine.CustomMultiArgv;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.testutil.Scratch;
 
 import org.junit.Before;
@@ -56,7 +56,7 @@
   }
 
   @Test
-  public void testLabelArgs() throws SyntaxException {
+  public void testLabelArgs() throws LabelSyntaxException {
     CustomCommandLine cl = CustomCommandLine.builder().add(Label.parseAbsolute("//a:b")).build();
     assertEquals(ImmutableList.of("//a:b"), cl.arguments());
   }
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/LabelExpanderTest.java b/src/test/java/com/google/devtools/build/lib/analysis/LabelExpanderTest.java
index 708408f..f574cef 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/LabelExpanderTest.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/LabelExpanderTest.java
@@ -17,8 +17,8 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.util.BuildViewTestCase;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.testutil.Suite;
 import com.google.devtools.build.lib.testutil.TestSpec;
 import com.google.devtools.build.lib.vfs.PathFragment;
@@ -88,7 +88,7 @@
   /**
    * Creates fake label in package "foo".
    */
-  private static Label labelFor(String targetName) throws SyntaxException {
+  private static Label labelFor(String targetName) throws LabelSyntaxException {
     return Label.create("foo", targetName);
   }
 
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/util/AnalysisTestCase.java b/src/test/java/com/google/devtools/build/lib/analysis/util/AnalysisTestCase.java
index 59a74a8..4e6e041 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/util/AnalysisTestCase.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/util/AnalysisTestCase.java
@@ -35,6 +35,7 @@
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.analysis.config.ConfigurationFactory;
 import com.google.devtools.build.lib.buildtool.BuildRequest.BuildRequestOptions;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.exec.ExecutionOptions;
 import com.google.devtools.build.lib.packages.PackageFactory;
 import com.google.devtools.build.lib.packages.Preprocessor;
@@ -53,7 +54,6 @@
 import com.google.devtools.build.lib.skyframe.SkyframeExecutor;
 import com.google.devtools.build.lib.skyframe.util.SkyframeExecutorTestUtils;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.testutil.FoundationTestCase;
 import com.google.devtools.build.lib.testutil.TestConstants;
 import com.google.devtools.build.lib.testutil.TestRuleClassProvider;
@@ -289,7 +289,7 @@
     try {
       return SkyframeExecutorTestUtils.getExistingTarget(skyframeExecutor,
           Label.parseAbsolute(label));
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new AssertionError(e);
     }
   }
@@ -304,7 +304,7 @@
     Label parsedLabel;
     try {
       parsedLabel = Label.parseAbsolute(label);
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new AssertionError(e);
     }
     return skyframeExecutor.getConfiguredTargetForTesting(parsedLabel, configuration);
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/util/BuildViewTestCase.java b/src/test/java/com/google/devtools/build/lib/analysis/util/BuildViewTestCase.java
index 641781f..ac9311d 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/util/BuildViewTestCase.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/util/BuildViewTestCase.java
@@ -76,6 +76,7 @@
 import com.google.devtools.build.lib.analysis.config.ConfigurationFactory;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
 import com.google.devtools.build.lib.buildtool.BuildRequest;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
@@ -113,7 +114,6 @@
 import com.google.devtools.build.lib.skyframe.SequencedSkyframeExecutor;
 import com.google.devtools.build.lib.skyframe.SkyValueDirtinessChecker;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.testutil.FoundationTestCase;
 import com.google.devtools.build.lib.testutil.MoreAsserts;
 import com.google.devtools.build.lib.testutil.TestConstants;
@@ -273,7 +273,7 @@
 
   protected Target getTarget(String label)
       throws NoSuchPackageException, NoSuchTargetException,
-             Label.SyntaxException, InterruptedException {
+      LabelSyntaxException, InterruptedException {
     return getTarget(Label.parseAbsolute(label));
   }
 
@@ -569,7 +569,8 @@
   }
 
   protected boolean ensureTargetsVisited(String... labels)
-      throws InterruptedException, NoSuchTargetException, NoSuchPackageException, SyntaxException {
+      throws InterruptedException, NoSuchTargetException, NoSuchPackageException,
+          LabelSyntaxException {
     List<Label> actualLabels = new ArrayList<>();
     for (String label : labels) {
       actualLabels.add(Label.parseAbsolute(label));
@@ -583,7 +584,7 @@
    */
   protected ConfiguredTarget getConfiguredTarget(String label)
       throws NoSuchPackageException, NoSuchTargetException,
-             Label.SyntaxException, InterruptedException {
+      LabelSyntaxException, InterruptedException {
     return getConfiguredTarget(label, targetConfig);
   }
 
@@ -593,7 +594,7 @@
    */
   protected ConfiguredTarget getConfiguredTarget(String label, BuildConfiguration config)
       throws NoSuchPackageException, NoSuchTargetException,
-             Label.SyntaxException, InterruptedException {
+      LabelSyntaxException, InterruptedException {
     ensureTargetsVisited(label);
     return view.getConfiguredTargetForTesting(getTarget(label), config);
   }
@@ -614,7 +615,7 @@
    */
   protected FileConfiguredTarget getFileConfiguredTarget(String label)
       throws NoSuchPackageException, NoSuchTargetException,
-             Label.SyntaxException, InterruptedException {
+      LabelSyntaxException, InterruptedException {
     return (FileConfiguredTarget) getConfiguredTarget(label, targetConfig);
   }
 
@@ -624,7 +625,7 @@
    */
   protected ConfiguredTarget getHostConfiguredTarget(String label)
       throws NoSuchPackageException, NoSuchTargetException,
-             Label.SyntaxException, InterruptedException {
+      LabelSyntaxException, InterruptedException {
     return getConfiguredTarget(label, getHostConfiguration());
   }
 
@@ -634,7 +635,7 @@
    */
   protected FileConfiguredTarget getHostFileConfiguredTarget(String label)
       throws NoSuchPackageException, NoSuchTargetException,
-             Label.SyntaxException, InterruptedException {
+      LabelSyntaxException, InterruptedException {
     return (FileConfiguredTarget) getHostConfiguredTarget(label);
   }
 
@@ -1070,7 +1071,7 @@
   private static Label makeLabel(String label) {
     try {
       return Label.parseAbsolute(label);
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new IllegalStateException(e);
     }
   }
@@ -1328,9 +1329,9 @@
    * Utility method for tests. Converts an array of strings into a set of labels.
    *
    * @param strings the set of strings to be converted to labels.
-   * @throws SyntaxException if there are any syntax errors in the strings.
+   * @throws LabelSyntaxException if there are any syntax errors in the strings.
    */
-  public static Set<Label> asLabelSet(String... strings) throws SyntaxException {
+  public static Set<Label> asLabelSet(String... strings) throws LabelSyntaxException {
     return asLabelSet(ImmutableList.copyOf(strings));
   }
 
@@ -1338,9 +1339,9 @@
    * Utility method for tests. Converts an array of strings into a set of labels.
    *
    * @param strings the set of strings to be converted to labels.
-   * @throws SyntaxException if there are any syntax errors in the strings.
+   * @throws LabelSyntaxException if there are any syntax errors in the strings.
    */
-  public static Set<Label> asLabelSet(Iterable<String> strings) throws SyntaxException {
+  public static Set<Label> asLabelSet(Iterable<String> strings) throws LabelSyntaxException {
     Set<Label> result = Sets.newTreeSet();
     for (String s : strings) {
       result.add(Label.parseAbsolute(s));
diff --git a/src/test/java/com/google/devtools/build/lib/cmdline/LabelValidatorTest.java b/src/test/java/com/google/devtools/build/lib/cmdline/LabelValidatorTest.java
index f14943d..547851f 100644
--- a/src/test/java/com/google/devtools/build/lib/cmdline/LabelValidatorTest.java
+++ b/src/test/java/com/google/devtools/build/lib/cmdline/LabelValidatorTest.java
@@ -98,6 +98,8 @@
     assertEquals(emptyPackage, LabelValidator.validateAbsoluteLabel("@repo//:bar"));
     assertEquals(new PackageAndTarget("foo", "bar"),
         LabelValidator.validateAbsoluteLabel("@repo//foo:bar"));
+    assertEquals(new PackageAndTarget("foo", "bar"),
+        LabelValidator.validateAbsoluteLabel("@//foo:bar"));
 
     try {
       LabelValidator.validateAbsoluteLabel("@foo");
diff --git a/src/test/java/com/google/devtools/build/lib/cmdline/PackageIdentifierTest.java b/src/test/java/com/google/devtools/build/lib/cmdline/PackageIdentifierTest.java
index 86f295b..f5ee2bf 100644
--- a/src/test/java/com/google/devtools/build/lib/cmdline/PackageIdentifierTest.java
+++ b/src/test/java/com/google/devtools/build/lib/cmdline/PackageIdentifierTest.java
@@ -49,6 +49,9 @@
     PackageIdentifier plainA = PackageIdentifier.parse("a");
     assertThat(plainA.getRepository().strippedName()).isEqualTo("");
     assertThat(fooA.getPackageFragment().getPathString()).isEqualTo("a");
+
+    PackageIdentifier mainA = PackageIdentifier.parse("@//a");
+    assertThat(mainA.getRepository()).isEqualTo(PackageIdentifier.MAIN_REPOSITORY_NAME);
   }
 
   @Test
@@ -59,45 +62,38 @@
     assertEquals("@foo/bar", RepositoryName.create("@foo/bar").toString());
     assertEquals("@foo.bar", RepositoryName.create("@foo.bar").toString());
 
-    // Bad:
-    try {
-      RepositoryName.create("@");
-      fail();
-    } catch (TargetParsingException expected) {
-      assertThat(expected.getMessage()).contains("empty workspace name");
-    }
     try {
       RepositoryName.create("@abc/");
       fail();
-    } catch (TargetParsingException expected) {
+    } catch (LabelSyntaxException expected) {
       assertThat(expected.getMessage()).contains(
           "workspace names cannot start nor end with '/'");
     }
     try {
       RepositoryName.create("@/abc");
       fail();
-    } catch (TargetParsingException expected) {
+    } catch (LabelSyntaxException expected) {
       assertThat(expected.getMessage()).contains(
           "workspace names cannot start nor end with '/'");
     }
     try {
       RepositoryName.create("@a//////b");
       fail();
-    } catch (TargetParsingException expected) {
+    } catch (LabelSyntaxException expected) {
       assertThat(expected.getMessage()).contains(
           "workspace names cannot contain multiple '/'s in a row");
     }
     try {
       RepositoryName.create("@foo@");
       fail();
-    } catch (TargetParsingException expected) {
+    } catch (LabelSyntaxException expected) {
       assertThat(expected.getMessage()).contains(
           "workspace names may contain only A-Z, a-z, 0-9, '-', '_', '.', and '/'");
     }
     try {
       RepositoryName.create("x");
       fail();
-    } catch (TargetParsingException expected) {
+    } catch (LabelSyntaxException expected) {
       assertThat(expected.getMessage()).contains("workspace name must start with '@'");
     }
   }
@@ -132,7 +128,7 @@
     try {
       new PackageIdentifier("foo", new PathFragment("bar/baz"));
       fail("'foo' is not a legal repository name");
-    } catch (TargetParsingException expected) {
+    } catch (LabelSyntaxException expected) {
       assertThat(expected.getMessage()).contains("workspace name must start with '@'");
     }
   }
diff --git a/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java b/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java
index f5041d2..9666b02 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java
@@ -34,6 +34,7 @@
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventCollector;
@@ -46,7 +47,6 @@
 import com.google.devtools.build.lib.packages.RuleClass.MissingFragmentPolicy;
 import com.google.devtools.build.lib.packages.util.PackageLoadingTestCase;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.vfs.Path;
 
 import java.util.ArrayList;
@@ -78,7 +78,7 @@
 
   private static final Predicate<String> PREFERRED_DEPENDENCY_PREDICATE = Predicates.alwaysFalse();
 
-  private static RuleClass createRuleClassA() throws Label.SyntaxException {
+  private static RuleClass createRuleClassA() throws LabelSyntaxException {
     return new RuleClass("ruleA", false, false, false, false, false, false,
         ImplicitOutputsFunction.NONE, RuleClass.NO_CHANGE,
         DUMMY_CONFIGURED_TARGET_FACTORY, PredicatesWithMessage.<Rule>alwaysTrue(),
@@ -650,12 +650,12 @@
   }
 
   private Rule createRule(RuleClass ruleClass, String name, Map<String, Object> attributeValues,
-      Location location) throws SyntaxException, InterruptedException {
+      Location location) throws LabelSyntaxException, InterruptedException {
     Package.Builder pkgBuilder = createDummyPackageBuilder();
     Label ruleLabel;
     try {
       ruleLabel = pkgBuilder.createLabel(name);
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new IllegalArgumentException("Rule has illegal label");
     }
     return ruleClass.createRuleWithLabel(pkgBuilder, ruleLabel, attributeValues,
diff --git a/src/test/java/com/google/devtools/build/lib/packages/util/PackageLoadingTestCase.java b/src/test/java/com/google/devtools/build/lib/packages/util/PackageLoadingTestCase.java
index dd44efc..7a73418 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/util/PackageLoadingTestCase.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/util/PackageLoadingTestCase.java
@@ -20,6 +20,7 @@
 import com.google.common.collect.Sets;
 import com.google.devtools.build.lib.analysis.BlazeDirectories;
 import com.google.devtools.build.lib.analysis.ConfiguredRuleClassProvider;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.packages.ConstantRuleVisibility;
 import com.google.devtools.build.lib.packages.NoSuchPackageException;
 import com.google.devtools.build.lib.packages.NoSuchTargetException;
@@ -38,7 +39,6 @@
 import com.google.devtools.build.lib.skyframe.SkyValueDirtinessChecker;
 import com.google.devtools.build.lib.skyframe.SkyframeExecutor;
 import com.google.devtools.build.lib.syntax.Label;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
 import com.google.devtools.build.lib.testutil.FoundationTestCase;
 import com.google.devtools.build.lib.testutil.TestRuleClassProvider;
 import com.google.devtools.build.lib.util.BlazeClock;
@@ -118,7 +118,7 @@
 
   protected Target getTarget(String label)
       throws NoSuchPackageException, NoSuchTargetException,
-             Label.SyntaxException, InterruptedException {
+      LabelSyntaxException, InterruptedException {
     return getTarget(Label.parseAbsolute(label));
   }
 
@@ -187,9 +187,9 @@
    * Utility method for tests. Converts an array of strings into a set of labels.
    *
    * @param strings the set of strings to be converted to labels.
-   * @throws SyntaxException if there are any syntax errors in the strings.
+   * @throws LabelSyntaxException if there are any syntax errors in the strings.
    */
-  public static Set<Label> asLabelSet(String... strings) throws SyntaxException {
+  public static Set<Label> asLabelSet(String... strings) throws LabelSyntaxException {
     return asLabelSet(ImmutableList.copyOf(strings));
   }
 
@@ -197,9 +197,9 @@
    * Utility method for tests. Converts an array of strings into a set of labels.
    *
    * @param strings the set of strings to be converted to labels.
-   * @throws SyntaxException if there are any syntax errors in the strings.
+   * @throws LabelSyntaxException if there are any syntax errors in the strings.
    */
-  public static Set<Label> asLabelSet(Iterable<String> strings) throws SyntaxException {
+  public static Set<Label> asLabelSet(Iterable<String> strings) throws LabelSyntaxException {
     Set<Label> result = Sets.newTreeSet();
     for (String s : strings) {
       result.add(Label.parseAbsolute(s));
@@ -208,12 +208,12 @@
   }
 
   protected final Set<Target> asTargetSet(String... strLabels)
-      throws SyntaxException, NoSuchThingException, InterruptedException {
+      throws LabelSyntaxException, NoSuchThingException, InterruptedException {
     return asTargetSet(Arrays.asList(strLabels));
   }
 
   protected Set<Target> asTargetSet(Iterable<String> strLabels)
-      throws SyntaxException, NoSuchThingException, InterruptedException {
+      throws LabelSyntaxException, NoSuchThingException, InterruptedException {
     Set<Target> targets = new HashSet<>();
     for (String strLabel : strLabels) {
       targets.add(getTarget(strLabel));
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/util/SkyframeExecutorTestUtils.java b/src/test/java/com/google/devtools/build/lib/skyframe/util/SkyframeExecutorTestUtils.java
index ea964ce..2867ea4 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/util/SkyframeExecutorTestUtils.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/util/SkyframeExecutorTestUtils.java
@@ -131,7 +131,7 @@
   public static Target getExistingTarget(SkyframeExecutor skyframeExecutor,
       Label label) {
     PackageValue value = (PackageValue) getExistingValue(skyframeExecutor,
-        PackageValue.key(label.getPackageFragment()));
+        PackageValue.key(label.getPackageIdentifier()));
     if (value == null) {
       return null;
     }
diff --git a/src/test/java/com/google/devtools/build/lib/syntax/EvalUtilsTest.java b/src/test/java/com/google/devtools/build/lib/syntax/EvalUtilsTest.java
index bf9672e..bcad177 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/EvalUtilsTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/EvalUtilsTest.java
@@ -20,6 +20,7 @@
 import static org.junit.Assert.assertTrue;
 
 import com.google.common.collect.Lists;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -55,7 +56,7 @@
       return new FilesetEntry(Label.parseAbsolute("//foo:bar"),
                               Lists.<Label>newArrayList(), Lists.newArrayList("xyz"), "",
                               FilesetEntry.SymlinkBehavior.COPY, ".");
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new RuntimeException("Bad label: ", e);
     }
   }
diff --git a/src/test/java/com/google/devtools/build/lib/syntax/LabelTest.java b/src/test/java/com/google/devtools/build/lib/syntax/LabelTest.java
index 322fb64..2ac874c 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/LabelTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/LabelTest.java
@@ -19,7 +19,7 @@
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.fail;
 
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.testutil.TestUtils;
 import com.google.devtools.build.lib.vfs.PathFragment;
 
@@ -60,7 +60,7 @@
     }
   }
 
-  private static String parseCommandLine(String label, String prefix) throws SyntaxException {
+  private static String parseCommandLine(String label, String prefix) throws LabelSyntaxException {
     return Label.parseCommandLineLabel(label, new PathFragment(prefix)).toString();
   }
 
@@ -91,7 +91,7 @@
     try {
       parseCommandLine("//absolute:A+bad%syntax", "");
       fail();
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       // Expected exception
     }
   }
@@ -112,25 +112,25 @@
     try {
       base.getRelative("/p1/p2:target");
       fail();
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       /* ok */
     }
     try {
       base.getRelative("quux:");
       fail();
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       /* ok */
     }
     try {
       base.getRelative(":");
       fail();
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       /* ok */
     }
     try {
       base.getRelative("::");
       fail();
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       /* ok */
     }
   }
@@ -186,7 +186,7 @@
     try {
       Label.parseAbsolute(label);
       fail("Label '" + label + "' did not contain a syntax error");
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       assertContainsRegex(Pattern.quote(expectedError), e.getMessage());
     }
   }
@@ -358,7 +358,7 @@
     try {
       Label.parseAbsolute("foo//bar/baz:bat/boo");
       fail();
-    } catch (SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       assertThat(e).hasMessage("invalid repository name 'foo': workspace name must start with '@'");
     }
   }
diff --git a/src/test/java/com/google/devtools/build/lib/syntax/PrinterTest.java b/src/test/java/com/google/devtools/build/lib/syntax/PrinterTest.java
index 21c1de1..63d5236 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/PrinterTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/PrinterTest.java
@@ -20,7 +20,7 @@
 
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Lists;
-import com.google.devtools.build.lib.syntax.Label.SyntaxException;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -52,7 +52,7 @@
       return new FilesetEntry(Label.parseAbsolute("//foo:bar"),
                               Lists.<Label>newArrayList(), Lists.newArrayList("xyz"), "",
                               FilesetEntry.SymlinkBehavior.COPY, ".");
-    } catch (Label.SyntaxException e) {
+    } catch (LabelSyntaxException e) {
       throw new RuntimeException("Bad label: ", e);
     }
   }
@@ -245,13 +245,13 @@
   }
 
   private FilesetEntry createTestFilesetEntry(FilesetEntry.SymlinkBehavior symlinkBehavior)
-      throws SyntaxException {
+      throws LabelSyntaxException {
     Label label = Label.parseAbsolute("//x");
     return new FilesetEntry(
         label, Arrays.asList(label), Arrays.<String>asList(), "", symlinkBehavior, ".");
   }
 
-  private FilesetEntry createTestFilesetEntry() throws SyntaxException {
+  private FilesetEntry createTestFilesetEntry() throws LabelSyntaxException {
     return createTestFilesetEntry(FilesetEntry.SymlinkBehavior.COPY);
   }
 }
diff --git a/src/tools/generate_workspace/src/main/java/com/google/devtools/build/workspace/Resolver.java b/src/tools/generate_workspace/src/main/java/com/google/devtools/build/workspace/Resolver.java
index 0feebe2..1b90378 100644
--- a/src/tools/generate_workspace/src/main/java/com/google/devtools/build/workspace/Resolver.java
+++ b/src/tools/generate_workspace/src/main/java/com/google/devtools/build/workspace/Resolver.java
@@ -16,8 +16,8 @@
 
 import com.google.devtools.build.lib.analysis.ConfiguredRuleClassProvider;
 import com.google.devtools.build.lib.bazel.BazelMain;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
-import com.google.devtools.build.lib.cmdline.TargetParsingException;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.events.Location;
@@ -94,7 +94,7 @@
         PackageIdentifier.RepositoryName repositoryName;
         try {
           repositoryName = PackageIdentifier.RepositoryName.create("@" + target.getName());
-        } catch (TargetParsingException e) {
+        } catch (LabelSyntaxException e) {
           handler.handle(Event.error(location, "Invalid repository name for " + target + ": "
               + e.getMessage()));
           return;