diff --git a/core/java/com/android/internal/os/Zygote.java b/core/java/com/android/internal/os/Zygote.java
index 1e7ee5a..4f6d781 100644
--- a/core/java/com/android/internal/os/Zygote.java
+++ b/core/java/com/android/internal/os/Zygote.java
@@ -17,6 +17,7 @@
 package com.android.internal.os;
 
 
+import android.os.Trace;
 import dalvik.system.ZygoteHooks;
 import android.system.ErrnoException;
 import android.system.Os;
@@ -88,6 +89,13 @@
         int pid = nativeForkAndSpecialize(
                   uid, gid, gids, debugFlags, rlimits, mountExternal, seInfo, niceName, fdsToClose,
                   instructionSet, appDataDir);
+        // Enable tracing as soon as possible for the child process.
+        if (pid == 0) {
+            Trace.setTracingEnabled(true);
+
+            // Note that this event ends at the end of handleChildProc,
+            Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "PostFork");
+        }
         VM_HOOKS.postForkCommon();
         return pid;
     }
@@ -124,6 +132,10 @@
         VM_HOOKS.preFork();
         int pid = nativeForkSystemServer(
                 uid, gid, gids, debugFlags, rlimits, permittedCapabilities, effectiveCapabilities);
+        // Enable tracing as soon as we enter the system_server.
+        if (pid == 0) {
+            Trace.setTracingEnabled(true);
+        }
         VM_HOOKS.postForkCommon();
         return pid;
     }