diff --git a/core/jni/AndroidRuntime.cpp b/core/jni/AndroidRuntime.cpp
index 20cb7a2..5611cc4 100644
--- a/core/jni/AndroidRuntime.cpp
+++ b/core/jni/AndroidRuntime.cpp
@@ -631,7 +631,7 @@
  *
  * Returns 0 on success.
  */
-int AndroidRuntime::startVm(JavaVM** pJavaVM, JNIEnv** pEnv, bool zygote)
+int AndroidRuntime::startVm(JavaVM** pJavaVM, JNIEnv** pEnv, bool zygote, bool primary_zygote)
 {
     JavaVMInitArgs initArgs;
     char propBuf[PROPERTY_VALUE_MAX];
@@ -762,6 +762,10 @@
     addOption("-verbose:gc");
     //addOption("-verbose:class");
 
+    if (primary_zygote) {
+        addOption("-Xprimaryzygote");
+    }
+
     /*
      * The default starting and maximum size of the heap.  Larger
      * values should be specified in a product property override.
@@ -1123,6 +1127,8 @@
             className != NULL ? className : "(unknown)", getuid());
 
     static const String8 startSystemServer("start-system-server");
+    // Whether this is the primary zygote, meaning the zygote which will fork system server.
+    bool primary_zygote = false;
 
     /*
      * 'startSystemServer == true' means runtime is obsolete and not run from
@@ -1130,6 +1136,7 @@
      */
     for (size_t i = 0; i < options.size(); ++i) {
         if (options[i] == startSystemServer) {
+            primary_zygote = true;
            /* track our progress through the boot sequence */
            const int LOG_BOOT_PROGRESS_START = 3000;
            LOG_EVENT_LONG(LOG_BOOT_PROGRESS_START,  ns2ms(systemTime(SYSTEM_TIME_MONOTONIC)));
@@ -1165,7 +1172,7 @@
     JniInvocation jni_invocation;
     jni_invocation.Init(NULL);
     JNIEnv* env;
-    if (startVm(&mJavaVM, &env, zygote) != 0) {
+    if (startVm(&mJavaVM, &env, zygote, primary_zygote) != 0) {
         return;
     }
     onVmCreated(env);
diff --git a/core/jni/include/android_runtime/AndroidRuntime.h b/core/jni/include/android_runtime/AndroidRuntime.h
index a19f954..2351272 100644
--- a/core/jni/include/android_runtime/AndroidRuntime.h
+++ b/core/jni/include/android_runtime/AndroidRuntime.h
@@ -131,7 +131,7 @@
                                     const char* runtimeArg,
                                     const char* quotingArg);
     void parseExtraOpts(char* extraOptsBuf, const char* quotingArg);
-    int startVm(JavaVM** pJavaVM, JNIEnv** pEnv, bool zygote);
+    int startVm(JavaVM** pJavaVM, JNIEnv** pEnv, bool zygote, bool primary_zygote);
 
     Vector<JavaVMOption> mOptions;
     bool mExitWithoutCleanup;