diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/ninja/actions/NinjaGraph.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/ninja/actions/NinjaGraph.java
index db819f5..42e8d8e 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/ninja/actions/NinjaGraph.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/ninja/actions/NinjaGraph.java
@@ -240,6 +240,10 @@
     Environment env = ruleContext.getAnalysisEnvironment().getSkyframeEnv();
     ImmutableSortedSet<String> notSymlinkedDirs =
         ExternalPackageUtil.getNotSymlinkedInExecrootDirectories(env);
+    if (env.valuesMissing()) {
+      return;
+    }
+
     // We can compare strings because notSymlinkedDirs contains normalized directory names
     if (!notSymlinkedDirs.contains(outputRoot.getPathString())) {
       ruleContext.attributeError(
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/LabelConstants.java b/src/main/java/com/google/devtools/build/lib/cmdline/LabelConstants.java
index 1608ed0..a110064 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/LabelConstants.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/LabelConstants.java
@@ -17,9 +17,22 @@
 
 /** Constants associated with {@code Label}s */
 public class LabelConstants {
+  /** The subdirectory under the output base which contains external repositories. */
+  public static final PathFragment EXTERNAL_REPOSITORY_LOCATION = PathFragment.create("external");
+
+  /**
+   * The path name under which external repositories are accessible if {@code
+   * --experimental_sibling_repository_layout} is not in effect.
+   */
   public static final PathFragment EXTERNAL_PACKAGE_NAME = PathFragment.create("external");
+
+  /**
+   * The name of the package containing information about external repositories if {@code
+   * --experimental_disable_external_package} is not in effect.
+   */
   public static final PackageIdentifier EXTERNAL_PACKAGE_IDENTIFIER =
       PackageIdentifier.createInMainRepo(EXTERNAL_PACKAGE_NAME);
+
   public static final PathFragment WORKSPACE_FILE_NAME = PathFragment.create("WORKSPACE");
   public static final PathFragment WORKSPACE_DOT_BAZEL_FILE_NAME =
       PathFragment.create("WORKSPACE.bazel");
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/RepositoryName.java b/src/main/java/com/google/devtools/build/lib/cmdline/RepositoryName.java
index 5f4d455..3e14d05 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/RepositoryName.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/RepositoryName.java
@@ -250,7 +250,7 @@
   public PathFragment getSourceRoot() {
     return isDefault() || isMain()
         ? PathFragment.EMPTY_FRAGMENT
-        : LabelConstants.EXTERNAL_PACKAGE_NAME.getRelative(strippedName());
+        : LabelConstants.EXTERNAL_REPOSITORY_LOCATION.getRelative(strippedName());
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/packages/StarlarkSemanticsOptions.java b/src/main/java/com/google/devtools/build/lib/packages/StarlarkSemanticsOptions.java
index 31c3218..3c82d52 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/StarlarkSemanticsOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/StarlarkSemanticsOptions.java
@@ -215,6 +215,20 @@
   public boolean experimentalRepoRemoteExec;
 
   @Option(
+      name = "experimental_disable_external_package",
+      defaultValue = "false",
+      documentationCategory = OptionDocumentationCategory.STARLARK_SEMANTICS,
+      effectTags = {OptionEffectTag.LOADING_AND_ANALYSIS, OptionEffectTag.LOSES_INCREMENTAL_STATE},
+      metadataTags = {
+        OptionMetadataTag.EXPERIMENTAL,
+      },
+      help =
+          "If set to true, the auto-generated //external package will not be available anymore. "
+              + "Bazel will still be unable to parse the file 'external/BUILD', but globs reaching "
+              + "into external/ from the unnamed package will work.")
+  public boolean experimentalDisableExternalPackage;
+
+  @Option(
       name = "experimental_sibling_repository_layout",
       defaultValue = "false",
       documentationCategory = OptionDocumentationCategory.STARLARK_SEMANTICS,
@@ -654,6 +668,7 @@
             .experimentalStarlarkUnusedInputsList(experimentalStarlarkUnusedInputsList)
             .experimentalCcSharedLibrary(experimentalCcSharedLibrary)
             .experimentalRepoRemoteExec(experimentalRepoRemoteExec)
+            .experimentalDisableExternalPackage(experimentalDisableExternalPackage)
             .experimentalSiblingRepositoryLayout(experimentalSiblingRepositoryLayout)
             .incompatibleApplicableLicenses(incompatibleApplicableLicenses)
             .incompatibleBzlDisallowLoadAfterStatement(incompatibleBzlDisallowLoadAfterStatement)
diff --git a/src/main/java/com/google/devtools/build/lib/query2/ParallelSkyQueryUtils.java b/src/main/java/com/google/devtools/build/lib/query2/ParallelSkyQueryUtils.java
index 24267e0..9e81dbd 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/ParallelSkyQueryUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/ParallelSkyQueryUtils.java
@@ -154,7 +154,7 @@
             /*resultUniquifier=*/ env.createSkyKeyUniquifier(),
             context,
             callback);
-    visitor.visitAndWaitForCompletion(env.getFileStateKeysForFileFragments(fileIdentifiers));
+    visitor.visitAndWaitForCompletion(env.getSkyKeysForFileFragments(fileIdentifiers));
   }
 
   static QueryTaskFuture<Void> getDepsUnboundedParallel(
@@ -234,4 +234,3 @@
     }
   }
 }
-
diff --git a/src/main/java/com/google/devtools/build/lib/query2/RBuildFilesVisitor.java b/src/main/java/com/google/devtools/build/lib/query2/RBuildFilesVisitor.java
index ed5dcd5..73b638c 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/RBuildFilesVisitor.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/RBuildFilesVisitor.java
@@ -16,7 +16,6 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.cmdline.Label;
-import com.google.devtools.build.lib.cmdline.LabelConstants;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.collect.compacthashset.CompactHashSet;
 import com.google.devtools.build.lib.packages.Target;
@@ -25,7 +24,6 @@
 import com.google.devtools.build.lib.query2.engine.QueryException;
 import com.google.devtools.build.lib.query2.engine.QueryExpressionContext;
 import com.google.devtools.build.lib.query2.engine.Uniquifier;
-import com.google.devtools.build.lib.skyframe.PackageValue;
 import com.google.devtools.build.lib.skyframe.SkyFunctions;
 import com.google.devtools.build.skyframe.SkyFunctionName;
 import com.google.devtools.build.skyframe.SkyKey;
@@ -54,8 +52,6 @@
           SkyFunctions.PREPARE_DEPS_OF_PATTERN,
           SkyFunctions.PREPARE_DEPS_OF_PATTERNS);
 
-  private static final SkyKey EXTERNAL_PACKAGE_KEY =
-      PackageValue.key(LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER);
   private final SkyQueryEnvironment env;
   private final QueryExpressionContext<Target> context;
   private final Uniquifier<SkyKey> visitUniquifier;
@@ -89,13 +85,6 @@
         if (resultUniquifier.unique(rdep)) {
           keysToUseForResult.add((PackageIdentifier) rdep.argument());
         }
-        // PackageValue(//p) has a transitive dep on the PackageValue(//external), so we need to
-        // make sure these dep paths are traversed. These dep paths go through the singleton
-        // WorkspaceNameValue(), and that node has a direct dep on PackageValue(//external), so it
-        // suffices to ensure we visit PackageValue(//external).
-        if (rdep.equals(EXTERNAL_PACKAGE_KEY)) {
-          keysToVisitNext.add(rdep);
-        }
       } else if (!NODES_TO_PRUNE_TRAVERSAL.contains(rdep.functionName())) {
         processNonPackageRdepAndDetermineVisitations(rdep, keysToVisitNext, keysToUseForResult);
       }
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 3678032..6f5e062 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
@@ -1211,15 +1211,8 @@
     return target;
   }
 
-  /**
-   * Returns package lookup keys for looking up the package root for which there may be a relevant
-   * (from the perspective of {@link #getRBuildFiles}) {@link FileStateValue} node in the graph for
-   * {@code originalFileFragment}, which is assumed to be a file path.
-   *
-   * <p>This is a helper function for {@link #getFileStateKeysForFileFragments}.
-   */
-  private static Iterable<SkyKey> getPkgLookupKeysForFile(PathFragment originalFileFragment,
-      PathFragment currentPathFragment) {
+  private static ImmutableList<SkyKey> getDependenciesForWorkspaceFile(
+      PathFragment originalFileFragment, PathFragment currentPathFragment) {
     if (originalFileFragment.equals(currentPathFragment)
         && WorkspaceFileHelper.matchWorkspaceFileName(originalFileFragment)) {
       // TODO(mschaller): this should not be checked at runtime. These are constants!
@@ -1228,10 +1221,29 @@
               .getParentDirectory()
               .equals(PathFragment.EMPTY_FRAGMENT),
           LabelConstants.WORKSPACE_FILE_NAME);
-      return ImmutableList.of(
-          PackageLookupValue.key(LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER),
-          PackageLookupValue.key(PackageIdentifier.createInMainRepo(PathFragment.EMPTY_FRAGMENT)));
+      // The WORKSPACE file is a transitive dependency of every package. Unfortunately, there is no
+      // specific SkyValue that we can use to figure out under which package path entries it lives,
+      // so we add another dependency that's a transitive dependency of every package.
+      //
+      // The PackageLookupValue for //external is not a good choice, because it's not requested when
+      // that package is built so that we can have a directory called external/ in the workspace
+      // (this is special-cased in PackageFunction). The principled solution would be to not rely
+      // on external/ and introduce a SkyValue for the concept of "the WORKSPACE file of the main
+      // repository", but we don't have that yet, so we improvise.
+      return ImmutableList.of(PackageValue.key(LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER));
     }
+
+    return ImmutableList.of();
+  }
+
+  /**
+   * Returns package lookup keys for looking up the package root for which there may be a relevant
+   * (from the perspective of {@link #getRBuildFiles}) {@link FileStateValue} node in the graph for
+   * {@code originalFileFragment}, which is assumed to be a file path.
+   *
+   * <p>This is a helper function for {@link #getSkyKeysForFileFragments}.
+   */
+  private static Iterable<SkyKey> getPkgLookupKeysForFile(PathFragment currentPathFragment) {
     PathFragment parentPathFragment = currentPathFragment.getParentDirectory();
     return parentPathFragment == null
         ? ImmutableList.of()
@@ -1240,19 +1252,26 @@
   }
 
   /**
-   * Returns FileStateValue keys for which there may be relevant (from the perspective of {@link
+   * Returns SkyKeys for which there may be relevant (from the perspective of {@link
    * #getRBuildFiles}) FileStateValues in the graph corresponding to the given {@code
    * pathFragments}, which are assumed to be file paths.
    *
-   * <p>To do this, we emulate the {@link ContainingPackageLookupFunction} logic: for each given
-   * file path, we look for the nearest ancestor directory (starting with its parent directory), if
-   * any, that has a package. The {@link PackageLookupValue} for this package tells us the package
-   * root that we should use for the {@link RootedPath} for the {@link FileStateValue} key.
+   * <p>The passed in {@link PathFragment}s can be associated uniquely to a {@link FileStateValue}
+   * with the following logic (the same logic that's in {@link ContainingPackageLookupFunction}):
+   * For each given file path, we look for the nearest ancestor directory (starting with its parent
+   * directory), if any, that has a package. The {@link PackageLookupValue} for this package tells
+   * us the package root that we should use for the {@link RootedPath} for the {@link
+   * FileStateValue} key.
+   *
+   * <p>For the reverse graph traversal in {@link #getRBuildFiles}, we are looking for all packages
+   * that are transitively reverse dependencies of those {@link FileStateValue} keys. This function
+   * returns a collection of SkyKeys whose transitive reverse dependencies must contain the exact
+   * same set of packages.
    *
    * <p>Note that there may not be nodes in the graph corresponding to the returned SkyKeys.
    */
-  protected Collection<SkyKey> getFileStateKeysForFileFragments(
-      Iterable<PathFragment> pathFragments) throws InterruptedException {
+  protected Collection<SkyKey> getSkyKeysForFileFragments(Iterable<PathFragment> pathFragments)
+      throws InterruptedException {
     Set<SkyKey> result = new HashSet<>();
     Multimap<PathFragment, PathFragment> currentToOriginal = ArrayListMultimap.create();
     for (PathFragment pathFragment : pathFragments) {
@@ -1264,10 +1283,12 @@
       for (Map.Entry<PathFragment, PathFragment> entry : currentToOriginal.entries()) {
         PathFragment current = entry.getKey();
         PathFragment original = entry.getValue();
-        for (SkyKey packageLookupKey : getPkgLookupKeysForFile(original, current)) {
+        for (SkyKey packageLookupKey : getPkgLookupKeysForFile(current)) {
           packageLookupKeysToOriginal.put(packageLookupKey, original);
           packageLookupKeysToCurrent.put(packageLookupKey, current);
         }
+
+        result.addAll(getDependenciesForWorkspaceFile(original, current));
       }
       Map<SkyKey, SkyValue> lookupValues =
           graph.getSuccessfulValues(packageLookupKeysToOriginal.keySet());
diff --git a/src/main/java/com/google/devtools/build/lib/repository/ExternalPackageUtil.java b/src/main/java/com/google/devtools/build/lib/repository/ExternalPackageUtil.java
index d5d558d..5b91936 100644
--- a/src/main/java/com/google/devtools/build/lib/repository/ExternalPackageUtil.java
+++ b/src/main/java/com/google/devtools/build/lib/repository/ExternalPackageUtil.java
@@ -14,14 +14,21 @@
 
 package com.google.devtools.build.lib.repository;
 
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSortedSet;
+import com.google.common.collect.Iterables;
+import com.google.devtools.build.lib.actions.FileValue;
 import com.google.devtools.build.lib.cmdline.LabelConstants;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.packages.BuildFileContainsErrorsException;
+import com.google.devtools.build.lib.packages.BuildFileName;
 import com.google.devtools.build.lib.packages.Package;
 import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.packages.WorkspaceFileValue;
-import com.google.devtools.build.lib.skyframe.PackageLookupValue;
+import com.google.devtools.build.lib.pkgcache.PathPackageLocator;
+import com.google.devtools.build.lib.skyframe.PrecomputedValue;
+import com.google.devtools.build.lib.vfs.PathFragment;
+import com.google.devtools.build.lib.vfs.Root;
 import com.google.devtools.build.lib.vfs.RootedPath;
 import com.google.devtools.build.skyframe.SkyFunction.Environment;
 import com.google.devtools.build.skyframe.SkyFunctionException.Transience;
@@ -68,16 +75,63 @@
     return extractor.getRule();
   }
 
+  private static RootedPath checkWorkspaceFile(
+      Environment env, Root root, PathFragment workspaceFile) throws InterruptedException {
+    RootedPath candidate = RootedPath.toRootedPath(root, workspaceFile);
+    FileValue fileValue = (FileValue) env.getValue(FileValue.key(candidate));
+    if (env.valuesMissing()) {
+      return null;
+    }
+
+    return fileValue.isFile() ? candidate : null;
+  }
+
+  /**
+   * Returns the path of the main WORKSPACE file or null when a Skyframe restart is required.
+   *
+   * <p>Should also return null when the WORKSPACE file is not present, but then some tests break,
+   * so then it lies and returns the RootedPath corresponding to the last package path entry.
+   */
+  @Nullable
+  public static RootedPath findWorkspaceFile(Environment env) throws InterruptedException {
+    PathPackageLocator packageLocator = PrecomputedValue.PATH_PACKAGE_LOCATOR.get(env);
+    ImmutableList<Root> packagePath = packageLocator.getPathEntries();
+    for (Root candidateRoot : packagePath) {
+      RootedPath path =
+          checkWorkspaceFile(
+              env, candidateRoot, BuildFileName.WORKSPACE_DOT_BAZEL.getFilenameFragment());
+      if (env.valuesMissing()) {
+        return null;
+      }
+
+      if (path != null) {
+        return path;
+      }
+
+      path = checkWorkspaceFile(env, candidateRoot, BuildFileName.WORKSPACE.getFilenameFragment());
+      if (env.valuesMissing()) {
+        return null;
+      }
+
+      if (path != null) {
+        return path;
+      }
+    }
+
+    // TODO(lberki): Technically, this means that the WORKSPACE file was not found. I'd love to not
+    // have this here, but a lot of tests break without it because they rely on Bazel kinda working
+    // even if the WORKSPACE file is not present.
+    return RootedPath.toRootedPath(
+        Iterables.getLast(packagePath), BuildFileName.WORKSPACE.getFilenameFragment());
+  }
+
   /** Returns false if some SkyValues were missing. */
   private static boolean iterateWorkspaceFragments(
       Environment env, WorkspaceFileValueProcessor processor) throws InterruptedException {
-    SkyKey packageLookupKey = PackageLookupValue.key(LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER);
-    PackageLookupValue packageLookupValue = (PackageLookupValue) env.getValue(packageLookupKey);
-    if (packageLookupValue == null) {
+    RootedPath workspacePath = findWorkspaceFile(env);
+    if (env.valuesMissing()) {
       return false;
     }
-    RootedPath workspacePath =
-        packageLookupValue.getRootedPath(LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER);
 
     SkyKey workspaceKey = WorkspaceFileValue.key(workspacePath);
     WorkspaceFileValue value;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryFunction.java b/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryFunction.java
index 8b8d82f..95b211b 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryFunction.java
@@ -533,7 +533,7 @@
   }
 
   protected static Path getExternalRepositoryDirectory(BlazeDirectories directories) {
-    return directories.getOutputBase().getRelative(LabelConstants.EXTERNAL_PACKAGE_NAME);
+    return directories.getOutputBase().getRelative(LabelConstants.EXTERNAL_REPOSITORY_LOCATION);
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ExternalFilesHelper.java b/src/main/java/com/google/devtools/build/lib/skyframe/ExternalFilesHelper.java
index 1fcbc4e..df04a16 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ExternalFilesHelper.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ExternalFilesHelper.java
@@ -245,7 +245,7 @@
       return FileType.EXTERNAL;
     }
     if (rootedPath.asPath().startsWith(outputBase)) {
-      Path externalRepoDir = outputBase.getRelative(LabelConstants.EXTERNAL_PACKAGE_NAME);
+      Path externalRepoDir = outputBase.getRelative(LabelConstants.EXTERNAL_REPOSITORY_LOCATION);
       if (rootedPath.asPath().startsWith(externalRepoDir)) {
         anyNonOutputExternalFilesSeen = true;
         return FileType.EXTERNAL_REPO;
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ExternalPackageFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ExternalPackageFunction.java
index 47791d5..71fa63a 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ExternalPackageFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ExternalPackageFunction.java
@@ -17,6 +17,7 @@
 import com.google.common.collect.Interner;
 import com.google.devtools.build.lib.concurrent.BlazeInterners;
 import com.google.devtools.build.lib.packages.WorkspaceFileValue;
+import com.google.devtools.build.lib.repository.ExternalPackageUtil;
 import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
 import com.google.devtools.build.lib.vfs.RootedPath;
 import com.google.devtools.build.skyframe.AbstractSkyKey;
@@ -27,17 +28,23 @@
 import javax.annotation.Nullable;
 
 /**
- * A SkyFunction for resolving //external:* bindings.
+ * A SkyFunction for parsing the {@code //external} package.
  *
  * <p>This function iterates through the WorkspaceFileValue-s to get the last WorkspaceFileValue
- * that will contains all the bind statements from the workspace file.
+ * that will contain all the bind statements from the WORKSPACE file.
  */
 public class ExternalPackageFunction implements SkyFunction {
 
   @Nullable
   @Override
   public SkyValue compute(SkyKey skyKey, Environment env) throws InterruptedException {
-    RootedPath workspacePath = (RootedPath) skyKey.argument();
+    RootedPath workspacePath = ExternalPackageUtil.findWorkspaceFile(env);
+    if (env.valuesMissing()) {
+      return null;
+    }
+
+    // This currently cannot be null due to a hack in ExternalPackageUtil.findWorkspaceFile()
+    // TODO(lberki): Remove that hack and handle the case when the WORKSPACE file is not found.
     SkyKey key = WorkspaceFileValue.key(workspacePath);
     WorkspaceFileValue value = (WorkspaceFileValue) env.getValue(key);
     if (value == null) {
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/LocalRepositoryLookupFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/LocalRepositoryLookupFunction.java
index 0e87677..86e21c1 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/LocalRepositoryLookupFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/LocalRepositoryLookupFunction.java
@@ -18,18 +18,17 @@
 import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.actions.FileValue;
 import com.google.devtools.build.lib.actions.InconsistentFilesystemException;
-import com.google.devtools.build.lib.cmdline.LabelConstants;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.packages.AggregatingAttributeMapper;
-import com.google.devtools.build.lib.packages.BuildFileNotFoundException;
 import com.google.devtools.build.lib.packages.ErrorDeterminingRepositoryException;
 import com.google.devtools.build.lib.packages.Package;
 import com.google.devtools.build.lib.packages.Package.NameConflictException;
 import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.packages.Type;
 import com.google.devtools.build.lib.packages.WorkspaceFileValue;
+import com.google.devtools.build.lib.repository.ExternalPackageUtil;
 import com.google.devtools.build.lib.rules.repository.LocalRepositoryRule;
 import com.google.devtools.build.lib.rules.repository.WorkspaceFileHelper;
 import com.google.devtools.build.lib.skyframe.PackageFunction.PackageFunctionException;
@@ -136,33 +135,11 @@
   private Optional<LocalRepositoryLookupValue> maybeCheckWorkspaceForRepository(
       Environment env, final RootedPath directory)
       throws InterruptedException, LocalRepositoryLookupFunctionException {
-    // Look up the main WORKSPACE file by the external package, to find all repositories.
-    PackageLookupValue externalPackageLookupValue;
-    try {
-      externalPackageLookupValue =
-          (PackageLookupValue)
-              env.getValueOrThrow(
-                  PackageLookupValue.key(LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER),
-                  BuildFileNotFoundException.class,
-                  InconsistentFilesystemException.class);
-      if (externalPackageLookupValue == null) {
-        return Optional.absent();
-      }
-    } catch (BuildFileNotFoundException e) {
-      throw new LocalRepositoryLookupFunctionException(
-          new ErrorDeterminingRepositoryException(
-              "BuildFileNotFoundException while loading the //external package", e),
-          Transience.PERSISTENT);
-    } catch (InconsistentFilesystemException e) {
-      throw new LocalRepositoryLookupFunctionException(
-          new ErrorDeterminingRepositoryException(
-              "InconsistentFilesystemException while loading the //external package", e),
-          Transience.PERSISTENT);
+    RootedPath workspacePath = ExternalPackageUtil.findWorkspaceFile(env);
+    if (env.valuesMissing()) {
+      return Optional.absent();
     }
 
-    RootedPath workspacePath =
-        externalPackageLookupValue.getRootedPath(LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER);
-
     SkyKey workspaceKey = WorkspaceFileValue.key(workspacePath);
     do {
       WorkspaceFileValue value;
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 92454ad..a4b7240 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
@@ -51,6 +51,7 @@
 import com.google.devtools.build.lib.profiler.Profiler;
 import com.google.devtools.build.lib.profiler.ProfilerTask;
 import com.google.devtools.build.lib.profiler.SilentCloseable;
+import com.google.devtools.build.lib.repository.ExternalPackageUtil;
 import com.google.devtools.build.lib.rules.repository.WorkspaceFileHelper;
 import com.google.devtools.build.lib.skyframe.GlobValue.InvalidGlobPatternException;
 import com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.SkylarkImportFailedException;
@@ -292,26 +293,14 @@
    * @throws PackageFunctionException if there is an error computing the workspace file or adding
    *     its rules to the //external package.
    */
-  private SkyValue getExternalPackage(Environment env, Root packageLookupPath)
+  private SkyValue getExternalPackage(Environment env)
       throws PackageFunctionException, InterruptedException {
     StarlarkSemantics starlarkSemantics = PrecomputedValue.STARLARK_SEMANTICS.get(env);
-    if (starlarkSemantics == null) {
+    RootedPath workspacePath = ExternalPackageUtil.findWorkspaceFile(env);
+    if (env.valuesMissing()) {
       return null;
     }
-    RootedPath workspacePath;
-    try {
-      workspacePath = WorkspaceFileHelper.getWorkspaceRootedFile(packageLookupPath, env);
-      if (workspacePath == null) {
-        return null;
-      }
-    } catch (IOException e) {
-      throw new PackageFunctionException(
-          new NoSuchPackageException(
-              LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER,
-              "Could not determine workspace file (\"WORKSPACE.bazel\" or \"WORKSPACE\"): "
-                  + e.getMessage()),
-          Transience.PERSISTENT);
-    }
+
     SkyKey workspaceKey = ExternalPackageFunction.key(workspacePath);
     PackageValue workspace = null;
     try {
@@ -355,6 +344,9 @@
   public SkyValue compute(SkyKey key, Environment env) throws PackageFunctionException,
       InterruptedException {
     PackageIdentifier packageId = (PackageIdentifier) key.argument();
+    if (packageId.equals(LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER)) {
+      return getExternalPackage(env);
+    }
 
     SkyKey packageLookupKey = PackageLookupValue.key(packageId);
     PackageLookupValue packageLookupValue;
@@ -394,9 +386,6 @@
       }
     }
 
-    if (packageId.equals(LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER)) {
-      return getExternalPackage(env, packageLookupValue.getRoot());
-    }
     WorkspaceNameValue workspaceNameValue =
         (WorkspaceNameValue) env.getValue(WorkspaceNameValue.key());
 
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 187b5d8..0249681 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
@@ -14,7 +14,7 @@
 package com.google.devtools.build.lib.skyframe;
 
 import com.google.common.base.Preconditions;
-import com.google.common.collect.ImmutableList;
+import com.google.common.base.Verify;
 import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.actions.FileValue;
 import com.google.devtools.build.lib.actions.InconsistentFilesystemException;
@@ -27,6 +27,7 @@
 import com.google.devtools.build.lib.packages.NoSuchPackageException;
 import com.google.devtools.build.lib.packages.RepositoryFetchException;
 import com.google.devtools.build.lib.pkgcache.PathPackageLocator;
+import com.google.devtools.build.lib.repository.ExternalPackageUtil;
 import com.google.devtools.build.lib.syntax.EvalException;
 import com.google.devtools.build.lib.syntax.StarlarkSemantics;
 import com.google.devtools.build.lib.vfs.PathFragment;
@@ -71,6 +72,7 @@
   public SkyValue compute(SkyKey skyKey, Environment env)
       throws PackageLookupFunctionException, InterruptedException {
     PathPackageLocator pkgLocator = PrecomputedValue.PATH_PACKAGE_LOCATOR.get(env);
+    StarlarkSemantics semantics = PrecomputedValue.STARLARK_SEMANTICS.get(env);
 
     PackageIdentifier packageKey = (PackageIdentifier) skyKey.argument();
 
@@ -87,8 +89,12 @@
 
     if (!packageKey.getRepository().isMain()) {
       return computeExternalPackageLookupValue(skyKey, env, packageKey);
-    } else if (packageKey.equals(LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER)) {
-      return computeWorkspacePackageLookupValue(env, pkgLocator.getPathEntries());
+    }
+
+    if (packageKey.equals(LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER)) {
+      return semantics.experimentalDisableExternalPackage()
+          ? PackageLookupValue.NO_BUILD_FILE_VALUE
+          : computeWorkspacePackageLookupValue(env);
     }
 
     // Check .bazelignore file under main repository.
@@ -194,30 +200,6 @@
 
   private PackageLookupValue getPackageLookupValue(
       Environment env,
-      ImmutableList<Root> packagePathEntries,
-      PackageIdentifier packageIdentifier,
-      BuildFileName buildFileName)
-      throws PackageLookupFunctionException, InterruptedException {
-
-    // TODO(bazel-team): The following is O(n^2) on the number of elements on the package path due
-    // to having restart the SkyFunction after every new dependency. However, if we try to batch
-    // the missing value keys, more dependencies than necessary will be declared. This wart can be
-    // fixed once we have nicer continuation support [skyframe-loading]
-    for (Root packagePathEntry : packagePathEntries) {
-      PackageLookupValue result =
-          getPackageLookupValue(env, packagePathEntry, packageIdentifier, buildFileName);
-      if (result == null) {
-        return null;
-      }
-      if (result != PackageLookupValue.NO_BUILD_FILE_VALUE) {
-        return result;
-      }
-    }
-    return PackageLookupValue.NO_BUILD_FILE_VALUE;
-  }
-
-  private PackageLookupValue getPackageLookupValue(
-      Environment env,
       Root packagePathEntry,
       PackageIdentifier packageIdentifier,
       BuildFileName buildFileName)
@@ -306,51 +288,29 @@
     return false;
   }
 
-  private PackageLookupValue computeWorkspacePackageLookupValue(
-      Environment env, ImmutableList<Root> packagePathEntries)
-      throws PackageLookupFunctionException, InterruptedException {
-    PackageLookupValue resultForWorkspaceDotBazel =
-        getPackageLookupValue(
-            env,
-            packagePathEntries,
-            LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER,
-            BuildFileName.WORKSPACE_DOT_BAZEL);
-    if (resultForWorkspaceDotBazel == null) {
+  private static PackageLookupValue computeWorkspacePackageLookupValue(Environment env)
+      throws InterruptedException {
+    RootedPath workspaceFile = ExternalPackageUtil.findWorkspaceFile(env);
+    if (env.valuesMissing()) {
       return null;
     }
-    if (resultForWorkspaceDotBazel.packageExists()) {
-      return resultForWorkspaceDotBazel;
-    }
-    PackageLookupValue resultForWorkspace =
-        getPackageLookupValue(
-            env,
-            packagePathEntries,
-            LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER,
-            BuildFileName.WORKSPACE);
-    if (resultForWorkspace == null) {
-      return null;
-    }
-    if (resultForWorkspace.packageExists()) {
-      return resultForWorkspace;
-    }
-    // Fall back on the last package path entry if there were any and nothing else worked.
-    // TODO(kchodorow): get rid of this, the semantics are wrong (successful package lookup should
-    // mean the package exists). a bunch of tests need to be rewritten first though.
-    if (packagePathEntries.isEmpty()) {
+
+    if (workspaceFile == null) {
       return PackageLookupValue.NO_BUILD_FILE_VALUE;
+    } else {
+      BuildFileName filename = null;
+      for (BuildFileName candidate : BuildFileName.values()) {
+        if (workspaceFile.getRootRelativePath().equals(candidate.getFilenameFragment())) {
+          filename = candidate;
+          break;
+        }
+      }
+
+      // Otherwise ExternalPackageUtil.findWorkspaceFile() returned something whose name is not in
+      // BuildFileName
+      Verify.verify(filename != null);
+      return PackageLookupValue.success(workspaceFile.getRoot(), filename);
     }
-    Root lastPackagePath = packagePathEntries.get(packagePathEntries.size() - 1);
-    FileValue lastPackagePackagePathFileValue =
-        getFileValue(
-            RootedPath.toRootedPath(lastPackagePath, PathFragment.EMPTY_FRAGMENT),
-            env,
-            LabelConstants.EXTERNAL_PACKAGE_IDENTIFIER);
-    if (lastPackagePackagePathFileValue == null) {
-      return null;
-    }
-    return lastPackagePackagePathFileValue.exists()
-        ? PackageLookupValue.success(lastPackagePath, BuildFileName.WORKSPACE)
-        : PackageLookupValue.NO_BUILD_FILE_VALUE;
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceFileFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceFileFunction.java
index 4736075..0e7c87f 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceFileFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceFileFunction.java
@@ -41,9 +41,7 @@
 import java.util.function.Function;
 import java.util.stream.Collectors;
 
-/**
- * A SkyFunction to parse WORKSPACE files.
- */
+/** A SkyFunction to parse the WORKSPACE file at a given path. */
 public class WorkspaceFileFunction implements SkyFunction {
 
   private final PackageFactory packageFactory;
@@ -68,9 +66,9 @@
       throws WorkspaceFileFunctionException, InterruptedException {
 
     WorkspaceFileKey key = (WorkspaceFileKey) skyKey.argument();
-    RootedPath workspaceRoot = key.getPath();
-    WorkspaceASTValue workspaceASTValue = (WorkspaceASTValue) env.getValue(
-        WorkspaceASTValue.key(workspaceRoot));
+    RootedPath workspaceFile = key.getPath();
+    WorkspaceASTValue workspaceASTValue =
+        (WorkspaceASTValue) env.getValue(WorkspaceASTValue.key(workspaceFile));
     if (workspaceASTValue == null) {
       return null;
     }
@@ -79,11 +77,9 @@
       return null;
     }
 
-    RootedPath repoWorkspace =
-        RootedPath.toRootedPath(workspaceRoot.getRoot(), workspaceRoot.getRootRelativePath());
     Package.Builder builder =
         packageFactory.newExternalPackageBuilder(
-            repoWorkspace, ruleClassProvider.getRunfilesPrefix(), starlarkSemantics);
+            workspaceFile, ruleClassProvider.getRunfilesPrefix(), starlarkSemantics);
 
     if (workspaceASTValue.getASTs().isEmpty()) {
       try {
@@ -92,7 +88,7 @@
             /* importMap = */ ImmutableMap.<String, Extension>of(),
             /* importToChunkMap = */ ImmutableMap.<String, Integer>of(),
             /* bindings = */ ImmutableMap.<String, Object>of(),
-            workspaceRoot,
+            workspaceFile,
             /* idx = */ 0, // first fragment
             /* hasNext = */ false,
             ImmutableMap.of(),
@@ -103,7 +99,7 @@
     }
     WorkspaceFactory parser;
     WorkspaceFileValue prevValue = null;
-    try (Mutability mutability = Mutability.create("workspace", repoWorkspace)) {
+    try (Mutability mutability = Mutability.create("workspace", workspaceFile)) {
       parser =
           new WorkspaceFactory(
               builder,
@@ -118,7 +114,7 @@
       if (key.getIndex() > 0) {
         prevValue =
             (WorkspaceFileValue)
-                env.getValue(WorkspaceFileValue.key(key.getPath(), key.getIndex() - 1));
+                env.getValue(WorkspaceFileValue.key(workspaceFile, key.getIndex() - 1));
         if (prevValue == null) {
           return null;
         }
@@ -130,7 +126,7 @@
       StarlarkFile ast = workspaceASTValue.getASTs().get(key.getIndex());
       PackageFunction.SkylarkImportResult importResult =
           PackageFunction.fetchImportsFromBuildFile(
-              repoWorkspace,
+              workspaceFile,
               rootPackage,
               /*repoMapping=*/ ImmutableMap.of(),
               ast,
@@ -153,7 +149,7 @@
           parser.getImportMap(),
           createImportToChunkMap(prevValue, parser, key),
           parser.getVariableBindings(),
-          workspaceRoot,
+          workspaceFile,
           key.getIndex(),
           key.getIndex() < workspaceASTValue.getASTs().size() - 1,
           ImmutableMap.copyOf(parser.getManagedDirectories()),
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/StarlarkSemantics.java b/src/main/java/com/google/devtools/build/lib/syntax/StarlarkSemantics.java
index 26bb70c..3278452 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/StarlarkSemantics.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/StarlarkSemantics.java
@@ -53,6 +53,8 @@
     public static final String EXPERIMENTAL_ACTION_ARGS = "experimental_action_args";
     public static final String EXPERIMENTAL_ALLOW_INCREMENTAL_REPOSITORY_UPDATES =
         "experimental_allow_incremental_repository_updates";
+    public static final String EXPERIMENTAL_DISABLE_EXTERNAL_PACKGE =
+        "experimental_disable_external_package";
     public static final String EXPERIMENTAL_SIBLING_REPOSITORY_LAYOUT =
         "experimental_sibling_repository_layout";
     public static final String EXPERIMENTAL_ASPECT_OUTPUT_PROPAGATION =
@@ -96,6 +98,8 @@
         return experimentalActionArgs();
       case FlagIdentifier.EXPERIMENTAL_ALLOW_INCREMENTAL_REPOSITORY_UPDATES:
         return experimentalAllowIncrementalRepositoryUpdates();
+      case FlagIdentifier.EXPERIMENTAL_DISABLE_EXTERNAL_PACKGE:
+        return experimentalDisableExternalPackage();
       case FlagIdentifier.EXPERIMENTAL_SIBLING_REPOSITORY_LAYOUT:
         return experimentalSiblingRepositoryLayout();
       case FlagIdentifier.EXPERIMENTAL_ASPECT_OUTPUT_PROPAGATION:
@@ -203,6 +207,8 @@
 
   public abstract boolean experimentalRepoRemoteExec();
 
+  public abstract boolean experimentalDisableExternalPackage();
+
   public abstract boolean experimentalSiblingRepositoryLayout();
 
   public abstract boolean incompatibleAlwaysCheckDepsetElements();
@@ -307,6 +313,7 @@
           .experimentalStarlarkUnusedInputsList(true)
           .experimentalCcSharedLibrary(false)
           .experimentalRepoRemoteExec(false)
+          .experimentalDisableExternalPackage(false)
           .experimentalSiblingRepositoryLayout(false)
           .incompatibleAlwaysCheckDepsetElements(false)
           .incompatibleApplicableLicenses(false)
@@ -371,6 +378,8 @@
 
     public abstract Builder experimentalRepoRemoteExec(boolean value);
 
+    public abstract Builder experimentalDisableExternalPackage(boolean value);
+
     public abstract Builder experimentalSiblingRepositoryLayout(boolean value);
 
     public abstract Builder incompatibleAlwaysCheckDepsetElements(boolean value);
diff --git a/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java b/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java
index b13f2dc..743d169 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java
@@ -121,6 +121,7 @@
         // <== Add new options here in alphabetic order ==>
         "--debug_depset_depth=" + rand.nextBoolean(),
         "--experimental_action_args=" + rand.nextBoolean(),
+        "--experimental_disable_external_package=" + rand.nextBoolean(),
         "--experimental_sibling_repository_layout=" + rand.nextBoolean(),
         "--experimental_allow_incremental_repository_updates=" + rand.nextBoolean(),
         "--experimental_aspect_output_propagation=" + rand.nextBoolean(),
@@ -175,6 +176,7 @@
         // <== Add new options here in alphabetic order ==>
         .debugDepsetDepth(rand.nextBoolean())
         .experimentalActionArgs(rand.nextBoolean())
+        .experimentalDisableExternalPackage(rand.nextBoolean())
         .experimentalSiblingRepositoryLayout(rand.nextBoolean())
         .experimentalAllowIncrementalRepositoryUpdates(rand.nextBoolean())
         .experimentalAspectOutputPropagation(rand.nextBoolean())
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/FileFunctionTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/FileFunctionTest.java
index ea3efbf..d173a20 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/FileFunctionTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/FileFunctionTest.java
@@ -391,7 +391,7 @@
   public void testAbsoluteSymlinkToExternal() throws Exception {
     String externalPath =
         outputBase
-            .getRelative(LabelConstants.EXTERNAL_PACKAGE_NAME)
+            .getRelative(LabelConstants.EXTERNAL_REPOSITORY_LOCATION)
             .getRelative("a/b")
             .getPathString();
     symlink("a", externalPath);
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/WorkspaceFileFunctionTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/WorkspaceFileFunctionTest.java
index 69e78aa..02b80ad 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/WorkspaceFileFunctionTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/WorkspaceFileFunctionTest.java
@@ -35,6 +35,7 @@
 import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.packages.WorkspaceFileValue;
 import com.google.devtools.build.lib.packages.WorkspaceFileValue.WorkspaceFileKey;
+import com.google.devtools.build.lib.pkgcache.PathPackageLocator;
 import com.google.devtools.build.lib.rules.repository.ManagedDirectoriesKnowledge;
 import com.google.devtools.build.lib.rules.repository.ManagedDirectoriesKnowledgeImpl;
 import com.google.devtools.build.lib.rules.repository.ManagedDirectoriesKnowledgeImpl.ManagedDirectoriesListener;
@@ -53,7 +54,6 @@
 import com.google.devtools.build.skyframe.SkyFunction;
 import com.google.devtools.build.skyframe.SkyFunctionName;
 import com.google.devtools.build.skyframe.SkyKey;
-import com.google.devtools.build.skyframe.SkyValue;
 import java.io.IOException;
 import java.util.Objects;
 import java.util.Set;
@@ -66,8 +66,6 @@
 import org.junit.runners.JUnit4;
 import org.mockito.Mockito;
 import org.mockito.hamcrest.MockitoHamcrest;
-import org.mockito.invocation.InvocationOnMock;
-import org.mockito.stubbing.Answer;
 
 /**
  * Test for {@link WorkspaceFileFunction}.
@@ -107,6 +105,11 @@
     }
 
     @Override
+    public boolean isFile() {
+      return exists;
+    }
+
+    @Override
     public ImmutableList<RootedPath> logicalChainDuringResolution() {
       throw new UnsupportedOperationException();
     }
@@ -183,46 +186,50 @@
   }
 
   private SkyFunction.Environment getEnv() throws InterruptedException {
+    PathPackageLocator locator = Mockito.mock(PathPackageLocator.class);
+    Mockito.when(locator.getPathEntries())
+        .thenReturn(ImmutableList.of(Root.fromPath(directories.getWorkspace())));
+
     SkyFunction.Environment env = Mockito.mock(SkyFunction.Environment.class);
     Mockito.when(env.getValue(MockitoHamcrest.argThat(new SkyKeyMatchers(FileValue.FILE))))
-        .thenReturn(fakeWorkspaceFileValue);
+        .then(
+            invocation -> {
+              SkyKey key = (SkyKey) invocation.getArguments()[0];
+              String path = ((RootedPath) key.argument()).getRootRelativePath().getPathString();
+              FakeFileValue result = new FakeFileValue();
+              result.setExists(path.equals("WORKSPACE"));
+              return result;
+            });
     Mockito.when(
             env.getValue(
                 MockitoHamcrest.argThat(new SkyKeyMatchers(WorkspaceFileValue.WORKSPACE_FILE))))
         .then(
-            new Answer<SkyValue>() {
-              @Override
-              public SkyValue answer(InvocationOnMock invocation) throws Throwable {
-                SkyKey key = (SkyKey) invocation.getArguments()[0];
-                return workspaceSkyFunc.compute(key, getEnv());
-              }
+            invocation -> {
+              SkyKey key = (SkyKey) invocation.getArguments()[0];
+              return workspaceSkyFunc.compute(key, getEnv());
             });
     Mockito.when(
             env.getValue(MockitoHamcrest.argThat(new SkyKeyMatchers(SkyFunctions.WORKSPACE_AST))))
         .then(
-            new Answer<SkyValue>() {
-              @Override
-              public SkyValue answer(InvocationOnMock invocation) throws Throwable {
-                SkyKey key = (SkyKey) invocation.getArguments()[0];
-                return astSkyFunc.compute(key, getEnv());
-              }
+            invocation -> {
+              SkyKey key = (SkyKey) invocation.getArguments()[0];
+              return astSkyFunc.compute(key, getEnv());
             });
     Mockito.when(
             env.getValue(MockitoHamcrest.argThat(new SkyKeyMatchers(SkyFunctions.PRECOMPUTED))))
         .then(
-            new Answer<SkyValue>() {
-              @Override
-              public SkyValue answer(InvocationOnMock invocation) throws Throwable {
-                SkyKey key = (SkyKey) invocation.getArguments()[0];
-                if (key.equals(PrecomputedValue.STARLARK_SEMANTICS.getKeyForTesting())) {
-                  return new PrecomputedValue(StarlarkSemantics.DEFAULT_SEMANTICS);
-                } else if (key.equals(
-                    RepositoryDelegatorFunction.RESOLVED_FILE_INSTEAD_OF_WORKSPACE
-                        .getKeyForTesting())) {
-                  return new PrecomputedValue(Optional.<RootedPath>absent());
-                } else {
-                  return null;
-                }
+            invocation -> {
+              SkyKey key = (SkyKey) invocation.getArguments()[0];
+              if (key.equals(PrecomputedValue.STARLARK_SEMANTICS.getKeyForTesting())) {
+                return new PrecomputedValue(StarlarkSemantics.DEFAULT_SEMANTICS);
+              } else if (key.equals(
+                  RepositoryDelegatorFunction.RESOLVED_FILE_INSTEAD_OF_WORKSPACE
+                      .getKeyForTesting())) {
+                return new PrecomputedValue(Optional.<RootedPath>absent());
+              } else if (key.equals(PrecomputedValue.PATH_PACKAGE_LOCATOR.getKeyForTesting())) {
+                return new PrecomputedValue(locator);
+              } else {
+                return null;
               }
             });
     return env;
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/WorkspaceNameFunctionTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/WorkspaceNameFunctionTest.java
index b290e8d..4d68c18 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/WorkspaceNameFunctionTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/WorkspaceNameFunctionTest.java
@@ -68,12 +68,10 @@
     reporter.removeHandler(failFastHandler);
     scratch.deleteFile("WORKSPACE");
     FileSystemUtils.ensureSymbolicLink(scratch.resolve("WORKSPACE"), "WORKSPACE");
-    // Transitive errors from WorkspaceNameValue should manifest themselves as
-    // NoSuchPackageExceptions.
     assertThatEvaluationResult(eval())
         .hasErrorEntryForKeyThat(key)
         .hasExceptionThat()
-        .isInstanceOf(NoSuchPackageException.class);
+        .isInstanceOf(FileSymlinkCycleException.class);
   }
 
   @Test
diff --git a/src/test/shell/bazel/execroot_test.sh b/src/test/shell/bazel/execroot_test.sh
index f0b842c..9c312e8 100755
--- a/src/test/shell/bazel/execroot_test.sh
+++ b/src/test/shell/bazel/execroot_test.sh
@@ -144,4 +144,68 @@
 
 }
 
+function test_external_directory_globs() {
+  touch WORKSPACE
+
+  mkdir -p external/a external/c
+  echo file_ab > external/a/b
+  echo file_cd > external/c/d
+  echo file_e > external/e
+  touch external/a/b external/c/d external/e
+
+  cat > BUILD <<'EOF'
+filegroup(name='f', srcs=glob(["**/*"]))
+genrule(name="g", srcs=[":f"], outs=["go"], cmd="cat $(locations :f) > $@")
+EOF
+
+  bazel build //:g \
+    --experimental_disable_external_package \
+    --experimental_sibling_repository_layout \
+    || fail "build failed"
+  assert_contains file_ab bazel-bin/go
+  assert_contains file_cd bazel-bin/go
+  assert_contains file_e bazel-bin/go
+}
+
+function test_cc_smoke_with_new_layouts() {
+  touch WORKSPACE
+  mkdir -p external/a
+  cat > external/a/BUILD <<EOF
+cc_binary(name='a', srcs=['a.cc'])
+EOF
+
+  cat > external/a/a.cc <<EOF
+int main(void) {
+  return 0;
+}
+EOF
+
+  bazel build //external/a:a \
+    --experimental_disable_external_package \
+    --experimental_sibling_repository_layout \
+    || fail "build failed"
+}
+
+function test_java_smoke_with_new_layouts() {
+  touch WORKSPACE
+  mkdir -p external/java/a
+  cat > external/java/a/BUILD <<EOF
+java_binary(name='a', srcs=['A.java'])
+EOF
+
+  cat > external/java/a/A.java << EOF
+package a;
+public class A {
+  public static void main(String[] args) {
+    System.out.println("hello world");
+  }
+}
+EOF
+
+  bazel build //external/java/a:a \
+    --experimental_disable_external_package \
+    --experimental_sibling_repository_layout \
+    || fail "build failed"
+}
+
 run_suite "execution root tests"