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 2924ffb1bf77d5..c69619ff4ba7a1 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
@@ -97,7 +97,8 @@ public CriticalPathComponent(int id, Action action, long startNanos) {
    * with the total spawn metrics. To make sure not to add the last phase's duration multiple times,
    * only add if there is duration and reset the phase metrics once it has been aggregated.
    */
-  public synchronized void finishActionExecution(long startNanos, long finishNanos) {
+  public synchronized void finishActionExecution(
+      long startNanos, long finishNanos, String finalizeReason) {
     if (isRunning || finishNanos - startNanos > getElapsedTimeNanos()) {
       this.startNanos = startNanos;
       this.finishNanos = finishNanos;
@@ -106,6 +107,13 @@ public synchronized void finishActionExecution(long startNanos, long finishNanos
       // this component.
       aggregatedElapsedTime = Math.max(aggregatedElapsedTime, this.finishNanos - this.startNanos);
       isRunning = false;
+      if (longestPhaseSpawnRunnerName == null && !finalizeReason.isEmpty()) {
+        // This is probably not the best way to do it in face of getting called multiple times.
+        longestPhaseSpawnRunnerName = finalizeReason;
+        longestPhaseSpawnRunnerSubtype = "";
+        longestRunningTotalDurationInMs =
+            (int) Duration.ofNanos(this.finishNanos - this.startNanos).toMillis();
+      }
     }
 
     // If the phaseMaxMetrics has Duration, then we want to aggregate it to the total.
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 ca2a00852529a3..6479de7ec826a4 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
@@ -251,7 +251,7 @@ public void middlemanAction(ActionMiddlemanEvent event) throws InterruptedExcept
     Action action = event.getAction();
     CriticalPathComponent component =
         tryAddComponent(createComponent(action, event.getNanoTimeStart()));
-    finalizeActionStat(event.getNanoTimeStart(), action, component);
+    finalizeActionStat(event.getNanoTimeStart(), action, component, "middleman action");
   }
 
   /**
@@ -312,7 +312,7 @@ public void actionCached(CachedActionEvent event) throws InterruptedException {
     Action action = event.getAction();
     CriticalPathComponent component =
         tryAddComponent(createComponent(action, event.getNanoTimeStart()));
-    finalizeActionStat(event.getNanoTimeStart(), action, component);
+    finalizeActionStat(event.getNanoTimeStart(), action, component, "action cache hit");
   }
 
   /**
@@ -326,7 +326,7 @@ public void actionComplete(ActionCompletionEvent event) {
     CriticalPathComponent component =
         Preconditions.checkNotNull(
             outputArtifactToComponent.get(action.getPrimaryOutput()), action);
-    finalizeActionStat(event.getRelativeActionStartTime(), action, component);
+    finalizeActionStat(event.getRelativeActionStartTime(), action, component, "");
   }
 
   /**
@@ -339,7 +339,8 @@ public void actionRewound(ActionRewoundEvent event) {
     Action action = event.getFailedRewoundAction();
     CriticalPathComponent component =
         Preconditions.checkNotNull(outputArtifactToComponent.get(action.getPrimaryOutput()));
-    component.finishActionExecution(event.getRelativeActionStartTime(), clock.nanoTime());
+    component.finishActionExecution(
+        event.getRelativeActionStartTime(), clock.nanoTime(), "action rewound");
   }
 
   /** Maximum critical path component found during the build. */
@@ -348,7 +349,7 @@ CriticalPathComponent getMaxCriticalPath() {
   }
 
   private void finalizeActionStat(
-      long startTimeNanos, Action action, CriticalPathComponent component) {
+      long startTimeNanos, Action action, CriticalPathComponent component, String finalizeReason) {
     long finishTimeNanos = clock.nanoTime();
     for (Artifact input : action.getInputs().toList()) {
       addArtifactDependency(component, input, finishTimeNanos);
@@ -359,7 +360,7 @@ private void finalizeActionStat(
           "Negative duration time for [%s] %s with start: %s, finish: %s.",
           action.getMnemonic(), action.getPrimaryOutput(), startTimeNanos, finishTimeNanos);
     }
-    component.finishActionExecution(startTimeNanos, finishTimeNanos);
+    component.finishActionExecution(startTimeNanos, finishTimeNanos, finalizeReason);
     maxCriticalPath.accumulateAndGet(component, SELECT_LONGER_COMPONENT);
   }