diff --git a/src/main/java/com/google/devtools/build/lib/actions/DiscoveredInputsEvent.java b/src/main/java/com/google/devtools/build/lib/actions/DiscoveredInputsEvent.java
new file mode 100644
index 0000000..fd1a36b
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/actions/DiscoveredInputsEvent.java
@@ -0,0 +1,42 @@
+// Copyright 2019 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.actions;
+
+import com.google.devtools.build.lib.events.ExtendedEventHandler;
+
+/** Event for passing SpawnMetrics for the discover inputs phase. */
+public class DiscoveredInputsEvent implements ExtendedEventHandler.ProgressLike {
+  private final SpawnMetrics metrics;
+  private final Action action;
+  private final long startTimeNanos;
+
+  public DiscoveredInputsEvent(SpawnMetrics metrics, Action action, long startTimeNanos) {
+    this.metrics = metrics;
+    this.action = action;
+    this.startTimeNanos = startTimeNanos;
+  }
+
+  public SpawnMetrics getMetrics() {
+    return metrics;
+  }
+
+  public Action getAction() {
+    return action;
+  }
+
+  public long getStartTimeNanos() {
+    return startTimeNanos;
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/CriticalPathComponent.java b/src/main/java/com/google/devtools/build/lib/runtime/CriticalPathComponent.java
index c6362324..1a60b07 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/CriticalPathComponent.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/CriticalPathComponent.java
@@ -57,7 +57,7 @@
   // These two fields are values of BlazeClock.nanoTime() at the relevant points in time.
   private long startNanos;
   private long finishNanos = 0;
-  private volatile boolean isRunning = true;
+  private volatile boolean isRunning = false;
 
   /** We keep here the critical path time for the most expensive child. */
   private long childAggregatedElapsedTime = 0;
@@ -138,6 +138,20 @@
     return action;
   }
 
+  /**
+   * This is called by {@link CriticalPathComputer#actionStarted} to start running the action. The
+   * three scenarios where this would occur is:
+   *
+   * <ol>
+   *   <li>A new CriticalPathComponent is created and should start running.
+   *   <li>A CriticalPathComponent has been created with discover inputs and beginning to execute.
+   *   <li>An action was rewound and starts again.
+   * </ol>
+   */
+  void startRunning() {
+    isRunning = true;
+  }
+
   public boolean isRunning() {
     return isRunning;
   }
@@ -165,26 +179,26 @@
   }
 
   /**
-   * An action can run multiple spawns. Those calls can be sequential or parallel. If it is a
-   * sequence of calls we should aggregate the metrics by collecting all the SpawnResults, if they
-   * are run in parallel we should keep the maximum runtime spawn. We will also set the
-   * longestPhaseSpawnRunnerName to the longest running spawn runner name across all phases.
+   * An action can run multiple spawns. Those calls can be sequential or parallel. If action is a
+   * sequence of calls we aggregate the SpawnMetrics of all the SpawnResults. If there are multiples
+   * of the same action run in parallel, we keep the maximum runtime SpawnMetrics. We will also set
+   * the longestPhaseSpawnRunnerName to the longest running spawn runner name across all phases if
+   * it exists.
    */
-  void addSpawnResult(SpawnResult spawnResult) {
+  void addSpawnResult(SpawnMetrics metrics, @Nullable String runnerName) {
     if (this.phaseChange) {
       this.totalSpawnMetrics =
           SpawnMetrics.aggregateMetrics(
               ImmutableList.of(this.totalSpawnMetrics, this.phaseMaxMetrics), true);
-      this.phaseMaxMetrics = spawnResult.getMetrics();
+      this.phaseMaxMetrics = metrics;
       this.phaseChange = false;
-    } else if (spawnResult.getMetrics().totalTime().compareTo(this.phaseMaxMetrics.totalTime())
-        > 0) {
-      this.phaseMaxMetrics = spawnResult.getMetrics();
+    } else if (metrics.totalTime().compareTo(this.phaseMaxMetrics.totalTime()) > 0) {
+      this.phaseMaxMetrics = metrics;
     }
 
-    if (spawnResult.getMetrics().totalTime().compareTo(this.longestRunningTotalDuration) > 0) {
-      this.longestPhaseSpawnRunnerName = spawnResult.getRunnerName();
-      this.longestRunningTotalDuration = spawnResult.getMetrics().totalTime();
+    if (runnerName != null && metrics.totalTime().compareTo(this.longestRunningTotalDuration) > 0) {
+      this.longestPhaseSpawnRunnerName = runnerName;
+      this.longestRunningTotalDuration = metrics.totalTime();
     }
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/CriticalPathComputer.java b/src/main/java/com/google/devtools/build/lib/runtime/CriticalPathComputer.java
index 632acd5..0dc987c 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/CriticalPathComputer.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/CriticalPathComputer.java
@@ -30,6 +30,7 @@
 import com.google.devtools.build.lib.actions.Actions;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.actions.CachedActionEvent;
+import com.google.devtools.build.lib.actions.DiscoveredInputsEvent;
 import com.google.devtools.build.lib.actions.SpawnExecutedEvent;
 import com.google.devtools.build.lib.actions.SpawnMetrics;
 import com.google.devtools.build.lib.actions.SpawnResult;
@@ -132,6 +133,7 @@
     return outputArtifactToComponent;
   }
 
+  /** Changes the phase of the action */
   @Subscribe
   @AllowConcurrentEvents
   public void nextCriticalPathPhase(SpawnExecutedEvent.ChangePhase phase) {
@@ -158,7 +160,7 @@
         Preconditions.checkNotNull(outputArtifactToComponent.get(primaryOutput));
 
     SpawnResult spawnResult = event.getSpawnResult();
-    stats.addSpawnResult(spawnResult);
+    stats.addSpawnResult(spawnResult.getMetrics(), spawnResult.getRunnerName());
   }
 
   /** Returns the list of components using the most memory. */
@@ -194,8 +196,19 @@
         .map((e) -> e.getValue());
   }
 
+  /** Creates a CriticalPathComponent and adds the duration of input discovery and changes phase. */
+  @Subscribe
+  @AllowConcurrentEvents
+  public void discoverInputs(DiscoveredInputsEvent event) {
+    CriticalPathComponent stats =
+        tryAddComponent(createComponent(event.getAction(), event.getStartTimeNanos()));
+    stats.addSpawnResult(event.getMetrics(), null);
+    stats.changePhase();
+  }
+
   /**
-   * Record an action that has started to run.
+   * Record an action that has started to run. If the CriticalPathComponent has not been created,
+   * initialize it and then start running.
    *
    * @param event information about the started action
    */
@@ -203,7 +216,7 @@
   @AllowConcurrentEvents
   public void actionStarted(ActionStartedEvent event) {
     Action action = event.getAction();
-    tryAddComponent(createComponent(action, event.getNanoTimeStart()));
+    tryAddComponent(createComponent(action, event.getNanoTimeStart())).startRunning();
   }
 
   /**
@@ -277,8 +290,8 @@
   @AllowConcurrentEvents
   public void actionCached(CachedActionEvent event) {
     Action action = event.getAction();
-    CriticalPathComponent component
-        = tryAddComponent(createComponent(action, event.getNanoTimeStart()));
+    CriticalPathComponent component =
+        tryAddComponent(createComponent(action, event.getNanoTimeStart()));
     finalizeActionStat(event.getNanoTimeStart(), action, component);
   }
 
@@ -339,24 +352,25 @@
     }
   }
 
-  protected void checkCriticalPathInconsistency(
-      Artifact.DerivedArtifact input, Action action, CriticalPathComponent actionStats) {
+  private void checkCriticalPathInconsistency(
+      Artifact.DerivedArtifact input, Action dependencyAction, CriticalPathComponent actionStats) {
     if (!checkCriticalPathInconsistencies) {
       return;
     }
     // Rare case that an action depending on a previously-cached shared action sees a different
     // shared action that is in the midst of being an action cache hit.
-    for (Artifact actionOutput : action.getOutputs()) {
+    for (Artifact actionOutput : dependencyAction.getOutputs()) {
       if (input.equals(actionOutput)
           && input
               .getGeneratingActionKey()
               .equals(((Artifact.DerivedArtifact) actionOutput).getGeneratingActionKey())) {
-        // As far as we can tell, this (currently running) action is the same action that
-        // produced input, not another shared action. This should be impossible.
+        // This (currently running) dependency action is the same action that produced the input for
+        // the finished actionStats CriticalPathComponent. This should be impossible.
         throw new IllegalStateException(
             String.format(
-                "Cannot add critical path stats when the action is not finished. %s. %s. %s",
-                input, actionStats.prettyPrintAction(), action));
+                "Cannot add critical path stats when the dependency action is not finished. "
+                    + "%s. %s. %s.",
+                input, actionStats.prettyPrintAction(), dependencyAction));
       }
     }
   }
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ActionExecutionFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ActionExecutionFunction.java
index 852a4d3..c685193 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ActionExecutionFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ActionExecutionFunction.java
@@ -38,6 +38,7 @@
 import com.google.devtools.build.lib.actions.AlreadyReportedActionExecutionException;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.actions.ArtifactPathResolver;
+import com.google.devtools.build.lib.actions.DiscoveredInputsEvent;
 import com.google.devtools.build.lib.actions.FileArtifactValue;
 import com.google.devtools.build.lib.actions.FilesetOutputSymlink;
 import com.google.devtools.build.lib.actions.LostInputsActionExecutionException;
@@ -45,6 +46,7 @@
 import com.google.devtools.build.lib.actions.MissingInputFileException;
 import com.google.devtools.build.lib.actions.NotifyOnActionCacheHit;
 import com.google.devtools.build.lib.actions.PackageRootResolver;
+import com.google.devtools.build.lib.actions.SpawnMetrics;
 import com.google.devtools.build.lib.actionsketch.ActionSketch;
 import com.google.devtools.build.lib.analysis.BlazeDirectories;
 import com.google.devtools.build.lib.causes.Cause;
@@ -78,6 +80,7 @@
 import com.google.devtools.build.skyframe.ValueOrException;
 import com.google.devtools.build.skyframe.ValueOrException2;
 import java.io.IOException;
+import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -820,6 +823,10 @@
                 e,
                 action,
                 /*catastrophe=*/ false);
+          } finally {
+            state.discoveredInputsDuration =
+                state.discoveredInputsDuration.plus(
+                    Duration.ofNanos(BlazeClock.nanoTime() - actionStartTime));
           }
           Preconditions.checkState(
               env.valuesMissing() == (state.discoveredInputs == null),
@@ -855,6 +862,16 @@
           // Set the MetadataHandler to accept output information.
           metadataHandler.discardOutputMetadata();
       }
+      // When discover inputs completes, post an event with the duration values.
+      env.getListener()
+          .post(
+              new DiscoveredInputsEvent(
+                  new SpawnMetrics.Builder()
+                      .setParseTime(state.discoveredInputsDuration)
+                      .setTotalTime(state.discoveredInputsDuration)
+                      .build(),
+                  action,
+                  actionStartTime));
     }
 
     try {
@@ -1332,6 +1349,7 @@
     Token token = null;
     Iterable<Artifact> discoveredInputs = null;
     FileSystem actionFileSystem = null;
+    Duration discoveredInputsDuration = Duration.ZERO;
 
     /**
      * Stores the ArtifactNestedSetKeys created from the inputs of this actions. Objective: avoid