diff --git a/aosp/binder_service_android.cc b/aosp/binder_service_android.cc
index 37df9a5..ec9ea6e 100644
--- a/aosp/binder_service_android.cc
+++ b/aosp/binder_service_android.cc
@@ -24,6 +24,7 @@
 #include <utils/String8.h>
 
 #include "update_engine/aosp/binder_service_android_common.h"
+#include "update_engine/common/error_code.h"
 
 using android::binder::Status;
 using android::os::IUpdateEngineCallback;
@@ -254,4 +255,14 @@
   return Status::ok();
 }
 
+Status BinderUpdateEngineAndroidService::triggerPostinstall(
+    const ::android::String16& partition) {
+  Error error;
+  service_delegate_->TriggerPostinstall(android::String8(partition).c_str(),
+                                        &error);
+  if (error.error_code != ErrorCode::kSuccess)
+    return ErrorPtrToStatus(error);
+  return Status::ok();
+}
+
 }  // namespace chromeos_update_engine
diff --git a/aosp/binder_service_android.h b/aosp/binder_service_android.h
index f1ce6b5..25d3c4b 100644
--- a/aosp/binder_service_android.h
+++ b/aosp/binder_service_android.h
@@ -33,8 +33,9 @@
 
 namespace chromeos_update_engine {
 
-class BinderUpdateEngineAndroidService : public android::os::BnUpdateEngine,
-                                         public ServiceObserverInterface {
+class BinderUpdateEngineAndroidService final
+    : public android::os::BnUpdateEngine,
+      public ServiceObserverInterface {
  public:
   explicit BinderUpdateEngineAndroidService(
       ServiceDelegateAndroidInterface* service_delegate);
@@ -79,6 +80,8 @@
       int64_t* return_value) override;
   android::binder::Status cleanupSuccessfulUpdate(
       const android::sp<android::os::IUpdateEngineCallback>& callback) override;
+  ::android::binder::Status triggerPostinstall(
+      const ::android::String16& partition) override;
 
  private:
   // Remove the passed |callback| from the list of registered callbacks. Called
diff --git a/aosp/update_engine_client_android.cc b/aosp/update_engine_client_android.cc
index 4f42a59..4d01ea6 100644
--- a/aosp/update_engine_client_android.cc
+++ b/aosp/update_engine_client_android.cc
@@ -157,6 +157,11 @@
                 "Perform just the slow switching part of OTA. "
                 "Used to revert a slot switch or re-do slot switch. Valid "
                 "values are 'true' and 'false'");
+  DEFINE_string(
+      trigger_postinstall,
+      UNSPECIFIED_FLAG,
+      "Only run postinstall sciprts. And only run postinstall script for the "
+      "specified partition. Example: \"system\", \"product\"");
   DEFINE_bool(suspend, false, "Suspend an ongoing update and exit.");
   DEFINE_bool(resume, false, "Resume a suspended update.");
   DEFINE_bool(cancel, false, "Cancel the ongoing update and exit.");
@@ -231,6 +236,11 @@
     return ExitWhenIdle(service_->resetStatus());
   }
 
+  if (FLAGS_trigger_postinstall != UNSPECIFIED_FLAG) {
+    return ExitWhenIdle(service_->triggerPostinstall(
+        android::String16(FLAGS_trigger_postinstall.c_str())));
+  }
+
   if (FLAGS_switch_slot != UNSPECIFIED_FLAG) {
     if (FLAGS_switch_slot != "true" && FLAGS_switch_slot != "false") {
       LOG(ERROR) << "--switch_slot should be either true or false, got "
diff --git a/binder_bindings/android/os/IUpdateEngine.aidl b/binder_bindings/android/os/IUpdateEngine.aidl
index 4043b1a..7291391 100644
--- a/binder_bindings/android/os/IUpdateEngine.aidl
+++ b/binder_bindings/android/os/IUpdateEngine.aidl
@@ -76,4 +76,23 @@
    * but needs reboot). DEVICE_CORRUPTED for permanent errors.
    */
   void cleanupSuccessfulUpdate(IUpdateEngineCallback callback);
+  /**
+   * Run postinstall scripts for the given |partition|
+   * This allows developers to run postinstall for a partition at
+   * a time they see fit. For example, they may wish to run postinstall
+   * script when device is IDLE and charging. This method would return
+   * immediately if |partition| is empty or does not correspond to any
+   * partitions on device. |partition| is expected to be unsuffixed, for
+   * example system,product,system_ext, etc.
+   * It is allowed to call this function multiple times with the same
+   * partition. Postinstall script for that partition would get run more
+   * than once. Owners of postinstall scripts should be designed to work
+   * correctly in such cases(idempotent). Note this expectation holds even
+   * without this API, and it has been so for years.
+   * @param Name of thje partition to run postinstall scripts. Should not
+   * contain slot suffix.(e.g. system,product,system_ext)
+   *
+   * @hide
+   */
+  void triggerPostinstall(in String partition);
 }