diff --git a/src/main/java/com/google/devtools/build/lib/actions/AbstractAction.java b/src/main/java/com/google/devtools/build/lib/actions/AbstractAction.java
index 3dc3e4b..a0dda9e 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/AbstractAction.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/AbstractAction.java
@@ -27,6 +27,7 @@
 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.packages.AspectDescriptor;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
@@ -44,6 +45,7 @@
 import java.io.IOException;
 import java.util.Collection;
 import java.util.Map;
+import java.util.Map.Entry;
 import javax.annotation.Nullable;
 
 /**
@@ -470,12 +472,29 @@
             .setOwner(owner.getLabel().toString())
             .setId(getKey())
             .setMnemonic(getMnemonic());
-    if (owner.getAspectName() != null) {
-      result.setAspectName(owner.getAspectName());
+    Iterable<AspectDescriptor> aspectDescriptors = owner.getAspectDescriptors();
+    AspectDescriptor lastAspect = null;
+
+    for (AspectDescriptor aspectDescriptor : aspectDescriptors) {
+      ExtraActionInfo.AspectDescriptor.Builder builder =
+          ExtraActionInfo.AspectDescriptor.newBuilder()
+            .setAspectName(aspectDescriptor.getAspectClass().getName());
+      for (Entry<String, Collection<String>> entry :
+          aspectDescriptor.getParameters().getAttributes().asMap().entrySet()) {
+          builder.putAspectParameters(
+            entry.getKey(),
+            ExtraActionInfo.AspectDescriptor.StringList.newBuilder()
+                .addAllValue(entry.getValue())
+                .build()
+          );
+      }
+      lastAspect = aspectDescriptor;
     }
-    if (owner.getAspectParameters() != null) {
+    if (lastAspect != null) {
+      result.setAspectName(lastAspect.getAspectClass().getName());
+
       for (Map.Entry<String, Collection<String>> entry :
-          owner.getAspectParameters().getAttributes().asMap().entrySet()) {
+          lastAspect.getParameters().getAttributes().asMap().entrySet()) {
         result.putAspectParameters(
             entry.getKey(),
             ExtraActionInfo.StringList.newBuilder().addAllValue(entry.getValue()).build());
diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionOwner.java b/src/main/java/com/google/devtools/build/lib/actions/ActionOwner.java
index b641a4d..72ca914 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionOwner.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionOwner.java
@@ -14,10 +14,11 @@
 package com.google.devtools.build.lib.actions;
 
 import com.google.auto.value.AutoValue;
+import com.google.common.collect.ImmutableList;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.events.Location;
-import com.google.devtools.build.lib.packages.AspectParameters;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.util.Preconditions;
 import javax.annotation.Nullable;
 
@@ -33,12 +34,12 @@
 public abstract class ActionOwner {
   /** An action owner for special cases. Usage is strongly discouraged. */
   public static final ActionOwner SYSTEM_ACTION_OWNER =
-      ActionOwner.create(null, null, null, null, "system", "empty target kind", "system", null);
+      ActionOwner.create(null, ImmutableList.<AspectDescriptor>of(),
+          null, "system", "empty target kind", "system", null);
 
   public static ActionOwner create(
       @Nullable Label label,
-      @Nullable String aspectName,
-      @Nullable AspectParameters aspectParameters,
+      ImmutableList<AspectDescriptor> aspectDescriptors,
       @Nullable Location location,
       @Nullable String mnemonic,
       @Nullable String targetKind,
@@ -47,8 +48,7 @@
     return new AutoValue_ActionOwner(
         location,
         label,
-        aspectName,
-        aspectParameters,
+        aspectDescriptors,
         mnemonic,
         Preconditions.checkNotNull(configurationChecksum),
         targetKind,
@@ -63,11 +63,7 @@
   @Nullable
   public abstract Label getLabel();
 
-  @Nullable
-  public abstract String getAspectName();
-
-  @Nullable
-  public abstract AspectParameters getAspectParameters();
+  public abstract ImmutableList<AspectDescriptor> getAspectDescriptors();
 
   /** Returns the configuration's mnemonic. */
   @Nullable
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/BuildView.java b/src/main/java/com/google/devtools/build/lib/analysis/BuildView.java
index 8f065ef..19e972c 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/BuildView.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/BuildView.java
@@ -51,6 +51,7 @@
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.events.StoredEventHandler;
 import com.google.devtools.build.lib.packages.AspectClass;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.AspectParameters;
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.BuildType;
@@ -1105,8 +1106,7 @@
     return new RuleContext.Builder(
             env,
             (Rule) target.getTarget(),
-            null,
-            null,
+            ImmutableList.<AspectDescriptor>of(),
             targetConfig,
             configurations.getHostConfiguration(),
             ruleClassProvider.getPrerequisiteValidator(),
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredAspect.java b/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredAspect.java
index 6196bce..ff90a87 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredAspect.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredAspect.java
@@ -27,6 +27,7 @@
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.packages.AspectClass;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.AspectParameters;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import com.google.devtools.build.lib.packages.SkylarkClassObjectConstructor.Key;
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredTargetFactory.java b/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredTargetFactory.java
index fdc0c74..11d03fa 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredTargetFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredTargetFactory.java
@@ -14,7 +14,11 @@
 
 package com.google.devtools.build.lib.analysis;
 
+import static com.google.common.collect.Iterables.transform;
+
+import com.google.common.base.Function;
 import com.google.common.base.Joiner;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.actions.ArtifactFactory;
@@ -32,6 +36,7 @@
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.packages.Aspect;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.ConfigurationFragmentPolicy;
 import com.google.devtools.build.lib.packages.ConfigurationFragmentPolicy.MissingFragmentPolicy;
@@ -227,8 +232,7 @@
         new RuleContext.Builder(
                 env,
                 rule,
-                null,
-                null,
+                ImmutableList.<AspectDescriptor>of(),
                 configuration,
                 hostConfiguration,
                 ruleClassProvider.getPrerequisiteValidator(),
@@ -304,6 +308,13 @@
     return result.toString();
   }
 
+  private static final Function<Aspect, AspectDescriptor> ASPECT_TO_DESCRIPTOR =
+      new Function<Aspect, AspectDescriptor>() {
+        @Override
+        public AspectDescriptor apply(Aspect aspect) {
+          return aspect.getDescriptor();
+        }
+      };
   /**
    * Constructs an {@link ConfiguredAspect}. Returns null if an error occurs; in that case,
    * {@code aspectFactory} should call one of the error reporting methods of {@link RuleContext}.
@@ -311,6 +322,7 @@
   public ConfiguredAspect createAspect(
       AnalysisEnvironment env,
       ConfiguredTarget associatedTarget,
+      ImmutableList<Aspect> aspectPath,
       ConfiguredAspectFactory aspectFactory,
       Aspect aspect,
       OrderedSetMultimap<Attribute, ConfiguredTarget> prerequisiteMap,
@@ -321,8 +333,7 @@
     RuleContext.Builder builder = new RuleContext.Builder(
         env,
         associatedTarget.getTarget().getAssociatedRule(),
-        aspect.getAspectClass().getName(),
-        aspect.getParameters(),
+        ImmutableList.copyOf(transform(aspectPath, ASPECT_TO_DESCRIPTOR)),
         aspectConfiguration,
         hostConfiguration,
         ruleClassProvider.getPrerequisiteValidator(),
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/Dependency.java b/src/main/java/com/google/devtools/build/lib/analysis/Dependency.java
index 755b991..d72bced 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/Dependency.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/Dependency.java
@@ -17,6 +17,7 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.util.Preconditions;
 import java.util.Map;
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/DependencyResolver.java b/src/main/java/com/google/devtools/build/lib/analysis/DependencyResolver.java
index 9fadc28..60d2747 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/DependencyResolver.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/DependencyResolver.java
@@ -28,6 +28,7 @@
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.packages.Aspect;
 import com.google.devtools.build.lib.packages.AspectClass;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.Attribute.LateBoundDefault;
 import com.google.devtools.build.lib.packages.AttributeMap;
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/MergedConfiguredTarget.java b/src/main/java/com/google/devtools/build/lib/analysis/MergedConfiguredTarget.java
index e067612..d5a4837 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/MergedConfiguredTarget.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/MergedConfiguredTarget.java
@@ -16,6 +16,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import com.google.devtools.build.lib.packages.SkylarkClassObjectConstructor.Key;
 import java.util.ArrayList;
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
index 202be7b..937cf74 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
@@ -53,7 +53,7 @@
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.Location;
-import com.google.devtools.build.lib.packages.AspectParameters;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition;
 import com.google.devtools.build.lib.packages.Attribute.SplitTransition;
@@ -151,8 +151,7 @@
   private static final String HOST_CONFIGURATION_PROGRESS_TAG = "for host";
 
   private final Rule rule;
-  @Nullable private final String aspectName;
-  @Nullable private final AspectParameters aspectParameters;
+  private final ImmutableList<AspectDescriptor> aspectDescriptors;
   private final ListMultimap<String, ConfiguredTarget> targetMap;
   private final ListMultimap<String, ConfiguredFilesetEntry> filesetEntryMap;
   private final ImmutableMap<Label, ConfigMatchingProvider> configConditions;
@@ -183,8 +182,7 @@
     super(builder.env, builder.rule, builder.configuration, builder.prerequisiteMap.get(null),
         builder.visibility);
     this.rule = builder.rule;
-    this.aspectName = builder.getAspectName();
-    this.aspectParameters = builder.getAspectParameters();
+    this.aspectDescriptors = builder.aspectDescriptors;
     this.configurationFragmentPolicy = builder.configurationFragmentPolicy;
     this.universalFragment = universalFragment;
     this.targetMap = targetMap;
@@ -334,7 +332,7 @@
   @Override
   public ActionOwner getActionOwner() {
     if (actionOwner == null) {
-      actionOwner = createActionOwner(rule, aspectName, aspectParameters, getConfiguration());
+      actionOwner = createActionOwner(rule, aspectDescriptors, getConfiguration());
     }
     return actionOwner;
   }
@@ -412,13 +410,11 @@
   @VisibleForTesting
   public static ActionOwner createActionOwner(
       Rule rule,
-      @Nullable String aspectName,
-      @Nullable AspectParameters aspectParameters,
+      ImmutableList<AspectDescriptor> aspectDescriptors,
       BuildConfiguration configuration) {
     return ActionOwner.create(
         rule.getLabel(),
-        aspectName,
-        aspectParameters,
+        aspectDescriptors,
         rule.getLocation(),
         configuration.getMnemonic(),
         rule.getTargetKind(),
@@ -1434,28 +1430,25 @@
     private final BuildConfiguration configuration;
     private final BuildConfiguration hostConfiguration;
     private final PrerequisiteValidator prerequisiteValidator;
-    @Nullable private final String aspectName;
-    @Nullable private final AspectParameters aspectParameters;
     private final ErrorReporter reporter;
     private OrderedSetMultimap<Attribute, ConfiguredTarget> prerequisiteMap;
     private ImmutableMap<Label, ConfigMatchingProvider> configConditions;
     private NestedSet<PackageSpecification> visibility;
     private ImmutableMap<String, Attribute> aspectAttributes;
     private ImmutableBiMap<String, Class<? extends TransitiveInfoProvider>> skylarkProviderRegistry;
+    private ImmutableList<AspectDescriptor> aspectDescriptors;
 
     Builder(
         AnalysisEnvironment env,
         Rule rule,
-        @Nullable String aspectName,
-        @Nullable AspectParameters aspectParameters,
+        ImmutableList<AspectDescriptor> aspectDescriptors,
         BuildConfiguration configuration,
         BuildConfiguration hostConfiguration,
         PrerequisiteValidator prerequisiteValidator,
         ConfigurationFragmentPolicy configurationFragmentPolicy) {
       this.env = Preconditions.checkNotNull(env);
       this.rule = Preconditions.checkNotNull(rule);
-      this.aspectName = aspectName;
-      this.aspectParameters = aspectParameters;
+      this.aspectDescriptors = aspectDescriptors;
       this.configurationFragmentPolicy = Preconditions.checkNotNull(configurationFragmentPolicy);
       this.configuration = Preconditions.checkNotNull(configuration);
       this.hostConfiguration = Preconditions.checkNotNull(hostConfiguration);
@@ -1736,7 +1729,7 @@
 
     /** Returns whether the context being constructed is for the evaluation of an aspect. */
     public boolean forAspect() {
-      return aspectName != null;
+      return !aspectDescriptors.isEmpty();
     }
 
     public Rule getRule() {
@@ -1747,9 +1740,11 @@
      * Returns a rule class name suitable for log messages, including an aspect name if applicable.
      */
     public String getRuleClassNameForLogging() {
-      return aspectName != null
-          ? aspectName + " aspect on " + rule.getRuleClass()
-          : rule.getRuleClass();
+      if (aspectDescriptors.isEmpty()) {
+        return rule.getRuleClass();
+      }
+
+      return Joiner.on(",").join(aspectDescriptors) + " aspect on " + rule.getRuleClass();
     }
 
     public BuildConfiguration getConfiguration() {
@@ -1959,16 +1954,6 @@
         prerequisiteValidator.validate(this, prerequisite, attribute);
       }
     }
-
-    @Nullable
-    public AspectParameters getAspectParameters() {
-      return aspectParameters;
-    }
-
-    @Nullable
-    public String getAspectName() {
-      return aspectName;
-    }
   }
 
   /**
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 c4689c9..05da5c8 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
@@ -33,7 +33,6 @@
 import com.google.common.collect.Multimap;
 import com.google.common.collect.MutableClassToInstanceMap;
 import com.google.devtools.build.lib.actions.Root;
-import com.google.devtools.build.lib.analysis.AspectDescriptor;
 import com.google.devtools.build.lib.analysis.BlazeDirectories;
 import com.google.devtools.build.lib.analysis.ConfiguredRuleClassProvider;
 import com.google.devtools.build.lib.analysis.Dependency;
@@ -44,6 +43,7 @@
 import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.Attribute.Configurator;
 import com.google.devtools.build.lib.packages.Attribute.SplitTransition;
diff --git a/src/main/java/com/google/devtools/build/lib/packages/Aspect.java b/src/main/java/com/google/devtools/build/lib/packages/Aspect.java
index 8e0be0c..817bc3c 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/Aspect.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/Aspect.java
@@ -30,20 +30,17 @@
   /** */
   public static final String INJECTING_RULE_KIND_PARAMETER_KEY = "$injecting_rule_kind";
 
-  // TODO(bazel-team): class objects are not really hashable or comparable for equality other than
-  // by reference. We should identify the aspect here in a way that does not rely on comparison
-  // by reference so that keys can be serialized and deserialized properly.
-  private final AspectClass aspectClass;
-  private final AspectParameters parameters;
+  private final AspectDescriptor aspectDescriptor;
   private final AspectDefinition aspectDefinition;
 
   private Aspect(
       AspectClass aspectClass,
       AspectDefinition aspectDefinition,
       AspectParameters parameters) {
-    this.aspectClass = Preconditions.checkNotNull(aspectClass);
+    this.aspectDescriptor = new AspectDescriptor(
+        Preconditions.checkNotNull(aspectClass),
+        Preconditions.checkNotNull(parameters));
     this.aspectDefinition = Preconditions.checkNotNull(aspectDefinition);
-    this.parameters = Preconditions.checkNotNull(parameters);
   }
 
   public static Aspect forNative(
@@ -66,19 +63,23 @@
    * Returns the aspectClass required for building the aspect.
    */
   public AspectClass getAspectClass() {
-    return aspectClass;
+    return aspectDescriptor.getAspectClass();
   }
 
   /**
    * Returns parameters for evaluation of the aspect.
    */
   public AspectParameters getParameters() {
-    return parameters;
+    return aspectDescriptor.getParameters();
+  }
+
+  public AspectDescriptor getDescriptor() {
+    return aspectDescriptor;
   }
 
   @Override
   public String toString() {
-    return String.format("Aspect %s(%s)", aspectClass, parameters);
+    return String.format("Aspect %s", aspectDescriptor.toString());
   }
 
   public AspectDefinition getDefinition() {
diff --git a/src/main/java/com/google/devtools/build/lib/packages/AspectClass.java b/src/main/java/com/google/devtools/build/lib/packages/AspectClass.java
index 2d615e1..e8c8cbe 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/AspectClass.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/AspectClass.java
@@ -72,7 +72,7 @@
  *    </li>
  *    <li>{@link AspectParameters} is a (key,value) pair list that can be used to
  *    parameterize aspect classes</li>
- *    <li>{@link com.google.devtools.build.lib.analysis.AspectDescriptor} is a pair
+ *    <li>{@link AspectDescriptor} is a pair
  *    of {@code AspectClass} and {@link AspectParameters}. It uniquely identifies
  *    the aspect and can be used in SkyKeys.
  *    </li>
@@ -89,7 +89,7 @@
  *    </li>
  *  </ul>
  *
- *  {@link com.google.devtools.build.lib.analysis.AspectDescriptor}, or in general, a tuple
+ *  {@link AspectDescriptor}, or in general, a tuple
  *  of ({@link AspectClass}, {@link AspectParameters}) is an identifier that should be
  *  used in SkyKeys or in other contexts that need equality for aspects.
  *  See also {@link com.google.devtools.build.lib.skyframe.AspectFunction} for details
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/AspectDescriptor.java b/src/main/java/com/google/devtools/build/lib/packages/AspectDescriptor.java
similarity index 94%
rename from src/main/java/com/google/devtools/build/lib/analysis/AspectDescriptor.java
rename to src/main/java/com/google/devtools/build/lib/packages/AspectDescriptor.java
index 2f56abb..0d6e743 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/AspectDescriptor.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/AspectDescriptor.java
@@ -12,12 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package com.google.devtools.build.lib.analysis;
+package com.google.devtools.build.lib.packages;
 
 import com.google.common.collect.ImmutableMultimap;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.packages.AspectClass;
-import com.google.devtools.build.lib.packages.AspectParameters;
 import com.google.protobuf.TextFormat;
 import java.util.Map.Entry;
 import java.util.Objects;
@@ -70,6 +68,11 @@
         && Objects.equals(aspectParameters, that.aspectParameters);
   }
 
+  @Override
+  public String toString() {
+    return getDescription();
+  }
+
   /**
    * Creates a presentable description of this aspect, avaliable
    * to Skylark via "Target.aspects".
diff --git a/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleContext.java b/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleContext.java
index 5042338..71aae06 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleContext.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleContext.java
@@ -24,7 +24,6 @@
 import com.google.devtools.build.lib.actions.Root;
 import com.google.devtools.build.lib.analysis.ActionsProvider;
 import com.google.devtools.build.lib.analysis.AnalysisUtils;
-import com.google.devtools.build.lib.analysis.AspectDescriptor;
 import com.google.devtools.build.lib.analysis.ConfigurationMakeVariableContext;
 import com.google.devtools.build.lib.analysis.FilesToRunProvider;
 import com.google.devtools.build.lib.analysis.LabelExpander;
@@ -38,6 +37,7 @@
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.events.Location;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition;
 import com.google.devtools.build.lib.packages.BuildType;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/extra/ExtraActionSpec.java b/src/main/java/com/google/devtools/build/lib/rules/extra/ExtraActionSpec.java
index 745cea0..748a7a5 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/extra/ExtraActionSpec.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/extra/ExtraActionSpec.java
@@ -28,6 +28,7 @@
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.util.Fingerprint;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import java.util.ArrayList;
@@ -236,10 +237,10 @@
   public static String getActionId(ActionOwner owner, Action action) {
     Fingerprint f = new Fingerprint();
     f.addString(owner.getLabel().toString());
-    f.addNullableString(owner.getAspectName());
-    f.addBoolean(owner.getAspectParameters() != null);
-    if (owner.getAspectParameters() != null) {
-      f.addString(owner.getAspectParameters().toString());
+    ImmutableList<AspectDescriptor> aspectDescriptors = owner.getAspectDescriptors();
+    f.addInt(aspectDescriptors.size());
+    for (AspectDescriptor aspectDescriptor : aspectDescriptors) {
+      f.addString(aspectDescriptor.getDescription());
     }
     f.addString(action.getKey());
     return f.hexDigestAndReset();
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/AspectFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/AspectFunction.java
index 4bf0f81..4f8835b 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/AspectFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/AspectFunction.java
@@ -216,7 +216,7 @@
     ConfiguredTarget associatedTarget =
       configuredTargetValue.getConfiguredTarget();
 
-    ImmutableList.Builder<Aspect> aspectPath = ImmutableList.builder();
+    ImmutableList.Builder<Aspect> aspectPathBuilder = ImmutableList.builder();
 
     if (key.getBaseKey() != null) {
       ImmutableList<SkyKey> aspectKeys = getSkyKeysForAspects(key.getBaseKey());
@@ -227,7 +227,7 @@
       }
       try {
         associatedTarget = getBaseTargetAndCollectPath(
-            associatedTarget, aspectKeys, values, aspectPath);
+            associatedTarget, aspectKeys, values, aspectPathBuilder);
       } catch (DuplicateException e) {
         env.getListener().handle(
             Event.error(associatedTarget.getTarget().getLocation(), e.getMessage()));
@@ -237,7 +237,7 @@
 
       }
     }
-    aspectPath.add(aspect);
+    aspectPathBuilder.add(aspect);
 
     SkyframeDependencyResolver resolver = view.createDependencyResolver(env);
 
@@ -249,6 +249,7 @@
     // will be present this way.
     TargetAndConfiguration originalTargetAndAspectConfiguration =
         new TargetAndConfiguration(target, key.getAspectConfiguration());
+    ImmutableList<Aspect> aspectPath = aspectPathBuilder.build();
     try {
       // Get the configuration targets that trigger this rule's configurable attributes.
       ImmutableMap<Label, ConfigMatchingProvider> configConditions =
@@ -266,7 +267,7 @@
             env,
             resolver,
             originalTargetAndAspectConfiguration,
-            aspectPath.build(),
+            aspectPath,
             configConditions,
             ruleClassProvider,
             view.getHostConfiguration(originalTargetAndAspectConfiguration.getConfiguration()),
@@ -286,7 +287,7 @@
       return createAspect(
           env,
           key,
-          target,
+          aspectPath,
           aspect,
           aspectFactory,
           associatedTarget,
@@ -387,7 +388,7 @@
   private AspectValue createAspect(
       Environment env,
       AspectKey key,
-      Target baseTarget,
+      ImmutableList<Aspect> aspectPath,
       Aspect aspect,
       ConfiguredAspectFactory aspectFactory,
       ConfiguredTarget associatedTarget,
@@ -410,6 +411,7 @@
         view.getConfiguredTargetFactory().createAspect(
             analysisEnvironment,
             associatedTarget,
+            aspectPath,
             aspectFactory,
             aspect,
             directDeps,
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/AspectValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/AspectValue.java
index d4366fa..7accbc1 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/AspectValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/AspectValue.java
@@ -16,7 +16,6 @@
 
 import com.google.common.base.Objects;
 import com.google.devtools.build.lib.actions.ActionAnalysisMetadata;
-import com.google.devtools.build.lib.analysis.AspectDescriptor;
 import com.google.devtools.build.lib.analysis.ConfiguredAspect;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.cmdline.Label;
@@ -24,6 +23,7 @@
 import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.packages.Aspect;
 import com.google.devtools.build.lib.packages.AspectClass;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.AspectParameters;
 import com.google.devtools.build.lib.packages.Package;
 import com.google.devtools.build.lib.syntax.SkylarkImport;
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ConfiguredTargetFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ConfiguredTargetFunction.java
index cc62260..134cea2 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ConfiguredTargetFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ConfiguredTargetFunction.java
@@ -31,7 +31,6 @@
 import com.google.devtools.build.lib.actions.Actions;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.actions.MutableActionGraph.ActionConflictException;
-import com.google.devtools.build.lib.analysis.AspectDescriptor;
 import com.google.devtools.build.lib.analysis.CachingAnalysisEnvironment;
 import com.google.devtools.build.lib.analysis.ConfiguredAspect;
 import com.google.devtools.build.lib.analysis.ConfiguredTarget;
@@ -56,6 +55,7 @@
 import com.google.devtools.build.lib.events.StoredEventHandler;
 import com.google.devtools.build.lib.packages.Aspect;
 import com.google.devtools.build.lib.packages.AspectDefinition;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.BuildType;
 import com.google.devtools.build.lib.packages.NoSuchTargetException;
@@ -78,7 +78,6 @@
 import com.google.devtools.build.skyframe.SkyValue;
 import com.google.devtools.build.skyframe.ValueOrException;
 import com.google.devtools.build.skyframe.ValueOrException2;
-
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
index a21158a..a93ee6b 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
@@ -50,7 +50,6 @@
 import com.google.devtools.build.lib.actions.PackageRootResolutionException;
 import com.google.devtools.build.lib.actions.ResourceManager;
 import com.google.devtools.build.lib.actions.Root;
-import com.google.devtools.build.lib.analysis.AspectDescriptor;
 import com.google.devtools.build.lib.analysis.BlazeDirectories;
 import com.google.devtools.build.lib.analysis.BuildView.Options;
 import com.google.devtools.build.lib.analysis.ConfiguredAspect;
@@ -79,6 +78,7 @@
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.events.Reporter;
 import com.google.devtools.build.lib.exec.OutputService;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.BuildFileContainsErrorsException;
 import com.google.devtools.build.lib.packages.NoSuchPackageException;
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkylarkAspectFactory.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkylarkAspectFactory.java
index 2608c7f..e80a788 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkylarkAspectFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkylarkAspectFactory.java
@@ -15,13 +15,13 @@
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
-import com.google.devtools.build.lib.analysis.AspectDescriptor;
 import com.google.devtools.build.lib.analysis.ConfiguredAspect;
 import com.google.devtools.build.lib.analysis.ConfiguredAspectFactory;
 import com.google.devtools.build.lib.analysis.ConfiguredTarget;
 import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.analysis.SkylarkProviderValidationUtil;
 import com.google.devtools.build.lib.events.Location;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.AspectParameters;
 import com.google.devtools.build.lib.packages.SkylarkAspect;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ToplevelSkylarkAspectFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ToplevelSkylarkAspectFunction.java
index 4d6dbf2..cc1aa44 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ToplevelSkylarkAspectFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ToplevelSkylarkAspectFunction.java
@@ -17,9 +17,9 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
-import com.google.devtools.build.lib.analysis.AspectDescriptor;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.events.Event;
+import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.AspectParameters;
 import com.google.devtools.build.lib.packages.SkylarkAspect;
 import com.google.devtools.build.lib.skyframe.AspectFunction.AspectCreationException;