diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkConfig.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkConfig.java
index bc4d6e4..061e0b5 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkConfig.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkConfig.java
@@ -21,69 +21,48 @@
 import static com.google.devtools.build.lib.syntax.Type.STRING;
 import static com.google.devtools.build.lib.syntax.Type.STRING_LIST;
 
+import com.google.devtools.build.lib.packages.BuildSetting;
 import com.google.devtools.build.lib.skylarkbuildapi.SkylarkConfigApi;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkPrinter;
-import com.google.devtools.build.lib.syntax.Type;
 
 /**
- * Skylark namespace for creating build setting descriptors.
+ * Skylark namespace for creating build settings.
+ * TODO(juliexxia): Consider adding more types of build settings, specifically other label types.
  */
 public class SkylarkConfig implements SkylarkConfigApi {
 
   @Override
-  public BuildSettingDescriptor intSetting(Boolean flag) {
-    return new BuildSettingDescriptor(flag, INTEGER);
+  public BuildSetting intSetting(Boolean flag) {
+    return new BuildSetting(flag, INTEGER);
   }
 
   @Override
-  public BuildSettingDescriptor boolSetting(Boolean flag) {
-    return new BuildSettingDescriptor(flag, BOOLEAN);
+  public BuildSetting boolSetting(Boolean flag) {
+    return new BuildSetting(flag, BOOLEAN);
   }
 
   @Override
-  public BuildSettingDescriptor stringSetting(Boolean flag) {
-    return new BuildSettingDescriptor(flag, STRING);
+  public BuildSetting stringSetting(Boolean flag) {
+    return new BuildSetting(flag, STRING);
   }
 
   @Override
-  public BuildSettingDescriptor stringListSetting(Boolean flag) {
-    return new BuildSettingDescriptor(flag, STRING_LIST);
+  public BuildSetting stringListSetting(Boolean flag) {
+    return new BuildSetting(flag, STRING_LIST);
   }
 
   @Override
-  public BuildSettingDescriptor labelSetting(Boolean flag) {
-    return new BuildSettingDescriptor(flag, LABEL);
+  public BuildSetting labelSetting(Boolean flag) {
+    return new BuildSetting(flag, LABEL);
   }
 
   @Override
-  public BuildSettingDescriptor labelListSetting(Boolean flag) {
-    return new BuildSettingDescriptor(flag, LABEL_LIST);
+  public BuildSetting labelListSetting(Boolean flag) {
+    return new BuildSetting(flag, LABEL_LIST);
   }
 
   @Override
   public void repr(SkylarkPrinter printer) {
     printer.append("<config>");
   }
-
-  /**
-   * An object that describes what time of build setting a skylark rule is (if any type).
-   */
-  private static final class BuildSettingDescriptor implements SkylarkConfigApi.BuildSettingApi {
-    private final boolean isFlag;
-    private final Type<?> type;
-
-    BuildSettingDescriptor(boolean isFlag, Type<?> type) {
-      this.isFlag = isFlag;
-      this.type = type;
-    }
-
-    public Type<?> getType() {
-      return type;
-    }
-
-    @Override
-    public void repr(SkylarkPrinter printer) {
-      printer.append("<build_setting." + type.toString() + ">");
-    }
-  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleClassFunctions.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleClassFunctions.java
index 264ae49..814cf5a 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleClassFunctions.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleClassFunctions.java
@@ -46,6 +46,7 @@
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.AttributeMap;
 import com.google.devtools.build.lib.packages.AttributeValueSource;
+import com.google.devtools.build.lib.packages.BuildSetting;
 import com.google.devtools.build.lib.packages.FunctionSplitTransitionWhitelist;
 import com.google.devtools.build.lib.packages.ImplicitOutputsFunction.SkylarkImplicitOutputsFunctionWithCallback;
 import com.google.devtools.build.lib.packages.ImplicitOutputsFunction.SkylarkImplicitOutputsFunctionWithMap;
@@ -272,6 +273,7 @@
       Boolean executionPlatformConstraintsAllowed,
       SkylarkList<?> execCompatibleWith,
       Object analysisTest,
+      Object buildSetting,
       FuncallExpression ast,
       Environment funcallEnv)
       throws EvalException, ConversionException {
@@ -352,6 +354,17 @@
     builder.addRequiredToolchains(
         collectToolchainLabels(
             toolchains.getContents(String.class, "toolchains"), ast.getLocation()));
+    if (!buildSetting.equals(Runtime.NONE)) {
+      if (funcallEnv.getSemantics().experimentalBuildSettingApi()) {
+        builder.setBuildSetting((BuildSetting) buildSetting);
+      } else {
+        throw new EvalException(
+            ast.getLocation(),
+            "build_setting parameter is experimental and not available for "
+                + "general use. It is subject to change at any time. It may be enabled by "
+                + "specifying --experimental_build_setting_api");
+      }
+    }
 
     for (Object o : providesArg) {
       if (!SkylarkAttr.isProvider(o)) {
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleContext.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleContext.java
index b311dfb..136ab55 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleContext.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleContext.java
@@ -14,6 +14,8 @@
 
 package com.google.devtools.build.lib.analysis.skylark;
 
+import static com.google.devtools.build.lib.packages.RuleClass.Builder.SKYLARK_BUILD_SETTING_DEFAULT_ATTR_NAME;
+
 import com.google.common.base.Function;
 import com.google.common.base.Optional;
 import com.google.common.base.Preconditions;
@@ -575,6 +577,30 @@
   }
 
   @Override
+  @Nullable
+  public Object getBuildSettingValue() throws EvalException {
+    if (ruleContext.getRule().getRuleClassObject().getBuildSetting() == null) {
+      throw new EvalException(
+          Location.BUILTIN,
+          String.format(
+              "attempting to access 'build_setting_value' of non-build setting %s",
+              ruleLabelCanonicalName));
+    }
+    ImmutableMap<String, Object> skylarkFlagSettings =
+        ruleContext.getConfiguration().getOptions().getSkylarkOptions();
+
+    Type<?> buildSettingType =
+        ruleContext.getRule().getRuleClassObject().getBuildSetting().getType();
+    if (skylarkFlagSettings.containsKey(ruleLabelCanonicalName)) {
+      return skylarkFlagSettings.get(ruleLabelCanonicalName);
+    } else {
+      return ruleContext
+          .attributes()
+          .get(SKYLARK_BUILD_SETTING_DEFAULT_ATTR_NAME, buildSettingType);
+    }
+  }
+
+  @Override
   public boolean instrumentCoverage(Object targetUnchecked) throws EvalException {
     checkMutable("coverage_instrumented");
     BuildConfiguration config = ruleContext.getConfiguration();
diff --git a/src/main/java/com/google/devtools/build/lib/packages/BuildSetting.java b/src/main/java/com/google/devtools/build/lib/packages/BuildSetting.java
new file mode 100644
index 0000000..506aaab
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/packages/BuildSetting.java
@@ -0,0 +1,47 @@
+// Copyright 2018 The Bazel Authors. 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.packages;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.devtools.build.lib.skylarkbuildapi.SkylarkConfigApi.BuildSettingApi;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkPrinter;
+import com.google.devtools.build.lib.syntax.Type;
+
+/**
+ * Metadata of a build setting rule's properties. This describes the build setting's type (for
+ * example, 'int' or 'string'), and whether the build setting corresponds to a command line flag.
+ */
+public class BuildSetting implements BuildSettingApi {
+  private final boolean isFlag;
+  private final Type<?> type;
+
+  public BuildSetting(boolean isFlag, Type<?> type) {
+    this.isFlag = isFlag;
+    this.type = type;
+  }
+
+  public Type<?> getType() {
+    return type;
+  }
+
+  @VisibleForTesting
+  public boolean isFlag() {
+    return isFlag;
+  }
+
+  @Override
+  public void repr(SkylarkPrinter printer) {
+    printer.append("<build_setting." + type + ">");
+  }
+}
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 fba2b88..56ceb24 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
@@ -57,6 +57,7 @@
 import com.google.devtools.build.lib.syntax.SkylarkList;
 import com.google.devtools.build.lib.syntax.Type;
 import com.google.devtools.build.lib.syntax.Type.ConversionException;
+import com.google.devtools.build.lib.util.FileTypeSet;
 import com.google.devtools.build.lib.util.StringUtil;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import java.util.ArrayList;
@@ -111,6 +112,8 @@
  *       tree. All targets appearing in these attributes appears beneath the ".runfiles" tree; in
  *       addition, "deps" may have rule-specific semantics.
  * </ul>
+ *
+ * TODO(bazel-team): Consider breaking up this class in more manageable subclasses.
  */
 // Non-final only for mocking in tests. Do not subclass!
 @Immutable
@@ -607,6 +610,12 @@
       }
     }
 
+    /**
+     * Name of default attribute implicitly added to all Skylark RuleClasses that are {@code
+     * build_setting}s.
+     */
+    public static final String SKYLARK_BUILD_SETTING_DEFAULT_ATTR_NAME = "build_setting_default";
+
     /** List of required attributes for normal rules, name and type. */
     public static final ImmutableList<Attribute> REQUIRED_ATTRIBUTES_FOR_NORMAL_RULES =
         ImmutableList.of(attr("tags", Type.STRING_LIST).build());
@@ -641,6 +650,7 @@
     private Predicate<String> preferredDependencyPredicate = Predicates.alwaysFalse();
     private AdvertisedProviderSet.Builder advertisedProviders = AdvertisedProviderSet.builder();
     private BaseFunction configuredTargetFunction = null;
+    private BuildSetting buildSetting = null;
     private Function<? super Rule, Map<String, Label>> externalBindingsFunction =
         NO_EXTERNAL_BINDINGS;
     private Function<? super Rule, ? extends Set<String>> optionReferenceFunction =
@@ -770,6 +780,17 @@
       if (skylark) {
         assertRuleClassProperStarlarkDefinedTransitionUsage();
       }
+      if (buildSetting != null) {
+        Type<?> type = buildSetting.getType();
+        Attribute.Builder<?> attrBuilder =
+            attr(SKYLARK_BUILD_SETTING_DEFAULT_ATTR_NAME, type)
+                .nonconfigurable("Build setting defaults are referenced during analysis.")
+                .mandatory();
+        if (BuildType.isLabelType(type)) {
+          attrBuilder.allowedFileTypes(FileTypeSet.ANY_FILE);
+        }
+        this.add(attrBuilder);
+      }
 
       return new RuleClass(
           name,
@@ -803,7 +824,8 @@
           executionPlatformConstraintsAllowed,
           executionPlatformConstraints,
           outputFileKind,
-          attributes.values());
+          attributes.values(),
+          buildSetting);
     }
 
     private void assertSkylarkRuleClassHasImplementationFunction() {
@@ -1142,6 +1164,11 @@
       return this;
     }
 
+    public Builder setBuildSetting(BuildSetting buildSetting) {
+      this.buildSetting = buildSetting;
+      return this;
+    }
+
     public Builder setExternalBindingsFunction(Function<? super Rule, Map<String, Label>> func) {
       this.externalBindingsFunction = func;
       return this;
@@ -1418,6 +1445,12 @@
   @Nullable private final BaseFunction configuredTargetFunction;
 
   /**
+   * The BuildSetting associated with this rule. Null for all RuleClasses except Skylark-defined
+   * rules that pass {@code build_setting} to their {@code rule()} declaration.
+   */
+  @Nullable private final BuildSetting buildSetting;
+
+  /**
    * Returns the extra bindings a workspace function adds to the WORKSPACE file.
    */
   private final Function<? super Rule, Map<String, Label>> externalBindingsFunction;
@@ -1506,7 +1539,8 @@
       ExecutionPlatformConstraintsAllowed executionPlatformConstraintsAllowed,
       Set<Label> executionPlatformConstraints,
       OutputFile.Kind outputFileKind,
-      Collection<Attribute> attributes) {
+      Collection<Attribute> attributes,
+      @Nullable BuildSetting buildSetting) {
     this.name = name;
     this.key = key;
     this.type = type;
@@ -1541,6 +1575,7 @@
     this.supportsPlatforms = supportsPlatforms;
     this.executionPlatformConstraintsAllowed = executionPlatformConstraintsAllowed;
     this.executionPlatformConstraints = ImmutableSet.copyOf(executionPlatformConstraints);
+    this.buildSetting = buildSetting;
 
     // Create the index and collect non-configurable attributes.
     int index = 0;
@@ -2307,6 +2342,11 @@
     return configuredTargetFunction;
   }
 
+  @Nullable
+  public BuildSetting getBuildSetting() {
+    return buildSetting;
+  }
+
   /**
    * Returns a function that computes the external bindings a repository function contributes to
    * the WORKSPACE file.
diff --git a/src/main/java/com/google/devtools/build/lib/packages/SkylarkSemanticsOptions.java b/src/main/java/com/google/devtools/build/lib/packages/SkylarkSemanticsOptions.java
index c57e823..55ae637 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/SkylarkSemanticsOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/SkylarkSemanticsOptions.java
@@ -72,6 +72,16 @@
   public boolean experimentalAnalysisTestingImprovements;
 
   @Option(
+      name = "experimental_build_setting_api",
+      defaultValue = "false",
+      documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
+      effectTags = OptionEffectTag.BUILD_FILE_SEMANTICS,
+      help =
+          "If set to true, allows access to value of build setting rules via "
+              + "ctx.build_setting_value.")
+  public boolean experimentalBuildSettingApi;
+
+  @Option(
       name = "experimental_cc_skylark_api_enabled_packages",
       converter = CommaSeparatedOptionListConverter.class,
       defaultValue = "",
@@ -520,6 +530,7 @@
     return SkylarkSemantics.builder()
         // <== Add new options here in alphabetic order ==>
         .experimentalAnalysisTestingImprovements(experimentalAnalysisTestingImprovements)
+        .experimentalBuildSettingApi(experimentalBuildSettingApi)
         .experimentalCcSkylarkApiEnabledPackages(experimentalCcSkylarkApiEnabledPackages)
         .experimentalEnableAndroidMigrationApis(experimentalEnableAndroidMigrationApis)
         .experimentalEnableRepoMapping(experimentalEnableRepoMapping)
diff --git a/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkRuleContextApi.java b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkRuleContextApi.java
index 979a447..20e04fa 100644
--- a/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkRuleContextApi.java
+++ b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkRuleContextApi.java
@@ -34,6 +34,7 @@
 import com.google.devtools.build.lib.syntax.SkylarkList;
 import com.google.devtools.build.lib.syntax.SkylarkList.Tuple;
 import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
+import com.google.devtools.build.lib.syntax.SkylarkSemantics.FlagIdentifier;
 import java.util.Map;
 import javax.annotation.Nullable;
 
@@ -229,6 +230,17 @@
   public BuildConfigurationApi getHostConfiguration() throws EvalException;
 
   @SkylarkCallable(
+      name = "build_setting_value",
+      structField = true,
+      enableOnlyWithFlag = FlagIdentifier.EXPERIMENTAL_BUILD_SETTING_API,
+      doc =
+          "<b>Experimental. This field is experimental and subject to change at any time. Do not "
+              + "depend on it.</b> <p>Returns the value of the build setting that is represented "
+              + "by the current target. It is an error to access this field for rules that do not "
+              + "set the <code>build_setting</code> attribute in their rule definition.")
+  public Object getBuildSettingValue() throws EvalException;
+
+  @SkylarkCallable(
       name = "coverage_instrumented",
       doc =
           "Returns whether code coverage instrumentation should be generated when performing "
diff --git a/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkRuleFunctionsApi.java b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkRuleFunctionsApi.java
index 247f01d..32d73f1 100644
--- a/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkRuleFunctionsApi.java
+++ b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkRuleFunctionsApi.java
@@ -16,6 +16,7 @@
 
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.events.Location;
+import com.google.devtools.build.lib.skylarkbuildapi.SkylarkConfigApi.BuildSettingApi;
 import com.google.devtools.build.lib.skylarkinterface.Param;
 import com.google.devtools.build.lib.skylarkinterface.ParamType;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
@@ -307,6 +308,20 @@
             doc =
                 "<b>Experimental: This parameter is experimental and subject to change at any "
                     + "time.</b><p> If true, then this rule is treated as an analysis test."),
+        @Param(
+            name = "build_setting",
+            type = BuildSettingApi.class,
+            noneable = true,
+            defaultValue = "None",
+            named = true,
+            positional = false,
+            // TODO(juliexxia): Link to in-build testing documentation when it is available.
+            doc =
+                "<b>Experimental: This parameter is experimental and subject to change at any "
+                    + "time.</b><p> If set, describes what kind of build setting this rule is. "
+                    + "See the <a href='config.html'><code>config</code></a> module. If this is "
+                    + "set, a mandatory attribute named \"build_setting_default\" is automatically"
+                    + "added to this rule, with a type corresponding to the value passed in here."),
       },
       useAst = true,
       useEnvironment = true)
@@ -326,6 +341,7 @@
       Boolean executionPlatformConstraintsAllowed,
       SkylarkList<?> execCompatibleWith,
       Object analysisTest,
+      Object buildSetting,
       FuncallExpression ast,
       Environment funcallEnv)
       throws EvalException;
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java
index db78fb1..4580e2e 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java
@@ -43,6 +43,7 @@
         SkylarkSemantics::experimentalAnalysisTestingImprovements),
     EXPERIMENTAL_ENABLE_ANDROID_MIGRATION_APIS(
         SkylarkSemantics::experimentalEnableAndroidMigrationApis),
+    EXPERIMENTAL_BUILD_SETTING_API(SkylarkSemantics::experimentalBuildSettingApi),
     EXPERIMENTAL_PLATFORM_API(SkylarkSemantics::experimentalPlatformsApi),
     INCOMPATIBLE_DISABLE_OBJC_PROVIDER_RESOURCES(
         SkylarkSemantics::incompatibleDisableObjcProviderResources),
@@ -109,6 +110,8 @@
   // <== Add new options here in alphabetic order ==>
   public abstract boolean experimentalAnalysisTestingImprovements();
 
+  public abstract boolean experimentalBuildSettingApi();
+
   public abstract List<String> experimentalCcSkylarkApiEnabledPackages();
 
   public abstract boolean experimentalEnableAndroidMigrationApis();
@@ -193,6 +196,7 @@
       builder()
           // <== Add new options here in alphabetic order ==>
           .experimentalAnalysisTestingImprovements(false)
+          .experimentalBuildSettingApi(false)
           .experimentalCcSkylarkApiEnabledPackages(ImmutableList.of())
           .experimentalEnableAndroidMigrationApis(false)
           .experimentalEnableRepoMapping(false)
@@ -236,6 +240,8 @@
     // <== Add new options here in alphabetic order ==>
     public abstract Builder experimentalAnalysisTestingImprovements(boolean value);
 
+    public abstract Builder experimentalBuildSettingApi(boolean value);
+
     public abstract Builder experimentalCcSkylarkApiEnabledPackages(List<String> value);
 
     public abstract Builder experimentalEnableAndroidMigrationApis(boolean value);
diff --git a/src/main/java/com/google/devtools/build/skydoc/fakebuildapi/FakeSkylarkRuleFunctionsApi.java b/src/main/java/com/google/devtools/build/skydoc/fakebuildapi/FakeSkylarkRuleFunctionsApi.java
index 29a7cb2..8b62d92 100644
--- a/src/main/java/com/google/devtools/build/skydoc/fakebuildapi/FakeSkylarkRuleFunctionsApi.java
+++ b/src/main/java/com/google/devtools/build/skydoc/fakebuildapi/FakeSkylarkRuleFunctionsApi.java
@@ -117,6 +117,7 @@
       Boolean executionPlatformConstraintsAllowed,
       SkylarkList<?> execCompatibleWith,
       Object analysisTest,
+      Object buildSetting,
       FuncallExpression ast,
       Environment funcallEnv)
       throws EvalException {
diff --git a/src/main/java/com/google/devtools/common/options/OptionsParser.java b/src/main/java/com/google/devtools/common/options/OptionsParser.java
index 9810988..331f2df 100644
--- a/src/main/java/com/google/devtools/common/options/OptionsParser.java
+++ b/src/main/java/com/google/devtools/common/options/OptionsParser.java
@@ -14,6 +14,7 @@
 
 package com.google.devtools.common.options;
 
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Joiner;
 import com.google.common.base.Preconditions;
 import com.google.common.base.Throwables;
@@ -197,7 +198,8 @@
     return skylarkOptions;
   }
 
-  void setSkylarkOptions(Map<String, Object> skylarkOptions) {
+  @VisibleForTesting
+  public void setSkylarkOptionsForTesting(Map<String, Object> skylarkOptions) {
     this.skylarkOptions = skylarkOptions;
   }