diff --git a/core/jni/android_util_AssetManager.cpp b/core/jni/android_util_AssetManager.cpp
index f96aef8..7162a1c 100644
--- a/core/jni/android_util_AssetManager.cpp
+++ b/core/jni/android_util_AssetManager.cpp
@@ -35,7 +35,16 @@
 #include <androidfw/AssetManager.h>
 #include <androidfw/ResourceTypes.h>
 
+#include <private/android_filesystem_config.h> // for AID_SYSTEM
+
 #include <stdio.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include <linux/capability.h>
+extern "C" int capget(cap_user_header_t hdrp, cap_user_data_t datap);
+extern "C" int capset(cap_user_header_t hdrp, const cap_user_data_t datap);
+
 
 namespace android {
 
@@ -100,6 +109,63 @@
     return block;
 }
 
+// This is called by zygote (running as user root) as part of preloadResources.
+static void verifySystemIdmaps()
+{
+    pid_t pid;
+    char system_id[10];
+
+    snprintf(system_id, sizeof(system_id), "%d", AID_SYSTEM);
+
+    switch (pid = fork()) {
+        case -1:
+            ALOGE("failed to fork for idmap: %s", strerror(errno));
+            break;
+        case 0: // child
+            {
+                struct __user_cap_header_struct capheader;
+                struct __user_cap_data_struct capdata;
+
+                memset(&capheader, 0, sizeof(capheader));
+                memset(&capdata, 0, sizeof(capdata));
+
+                capheader.version = _LINUX_CAPABILITY_VERSION;
+                capheader.pid = 0;
+
+                if (capget(&capheader, &capdata) != 0) {
+                    ALOGE("capget: %s\n", strerror(errno));
+                    exit(1);
+                }
+
+                capdata.effective = capdata.permitted;
+                if (capset(&capheader, &capdata) != 0) {
+                    ALOGE("capset: %s\n", strerror(errno));
+                    exit(1);
+                }
+
+                if (setgid(AID_SYSTEM) != 0) {
+                    ALOGE("setgid: %s\n", strerror(errno));
+                    exit(1);
+                }
+
+                if (setuid(AID_SYSTEM) != 0) {
+                    ALOGE("setuid: %s\n", strerror(errno));
+                    exit(1);
+                }
+
+                execl(AssetManager::IDMAP_BIN, AssetManager::IDMAP_BIN, "--scan",
+                        AssetManager::OVERLAY_DIR, AssetManager::TARGET_PACKAGE_NAME,
+                        AssetManager::TARGET_APK_PATH, AssetManager::IDMAP_DIR, (char*)NULL);
+                ALOGE("failed to execl for idmap: %s", strerror(errno));
+                exit(1); // should never get here
+            }
+            break;
+        default: // parent
+            waitpid(pid, NULL, 0);
+            break;
+    }
+}
+
 // ----------------------------------------------------------------------------
 
 // this guy is exported to other jni routines
@@ -444,6 +510,25 @@
     return (res) ? static_cast<jint>(cookie) : 0;
 }
 
+static jint android_content_AssetManager_addOverlayPath(JNIEnv* env, jobject clazz,
+                                                     jstring idmapPath)
+{
+    ScopedUtfChars idmapPath8(env, idmapPath);
+    if (idmapPath8.c_str() == NULL) {
+        return 0;
+    }
+
+    AssetManager* am = assetManagerForJavaObject(env, clazz);
+    if (am == NULL) {
+        return 0;
+    }
+
+    int32_t cookie;
+    bool res = am->addOverlayPath(String8(idmapPath8.c_str()), &cookie);
+
+    return (res) ? (jint)cookie : 0;
+}
+
 static jboolean android_content_AssetManager_isUpToDate(JNIEnv* env, jobject clazz)
 {
     AssetManager* am = assetManagerForJavaObject(env, clazz);
@@ -1579,8 +1664,11 @@
     return array;
 }
 
-static void android_content_AssetManager_init(JNIEnv* env, jobject clazz)
+static void android_content_AssetManager_init(JNIEnv* env, jobject clazz, jboolean isSystem)
 {
+    if (isSystem) {
+        verifySystemIdmaps();
+    }
     AssetManager* am = new AssetManager();
     if (am == NULL) {
         jniThrowException(env, "java/lang/OutOfMemoryError", "");
@@ -1658,6 +1746,8 @@
         (void*) android_content_AssetManager_getAssetRemainingLength },
     { "addAssetPathNative", "(Ljava/lang/String;)I",
         (void*) android_content_AssetManager_addAssetPath },
+    { "addOverlayPath",   "(Ljava/lang/String;)I",
+        (void*) android_content_AssetManager_addOverlayPath },
     { "isUpToDate",     "()Z",
         (void*) android_content_AssetManager_isUpToDate },
 
@@ -1724,7 +1814,7 @@
         (void*) android_content_AssetManager_getArrayIntResource },
 
     // Bookkeeping.
-    { "init",           "()V",
+    { "init",           "(Z)V",
         (void*) android_content_AssetManager_init },
     { "destroy",        "()V",
         (void*) android_content_AssetManager_destroy },