diff --git a/core/res/res/values/config.xml b/core/res/res/values/config.xml
index ce5d07c1e6ed3..51cd0299b4f2a 100644
--- a/core/res/res/values/config.xml
+++ b/core/res/res/values/config.xml
@@ -805,6 +805,13 @@
     -->
     <integer name="config_longPressOnPowerBehavior">1</integer>
 
+    <!-- Control the behavior when the user long presses the back button.  Non-zero values are only
+         valid for watches as part of CDD/CTS.
+            0 - Nothing
+            1 - Go to voice assist
+    -->
+    <integer name="config_longPressOnBackBehavior">0</integer>
+
     <!-- Control the behavior when the user short presses the power button.
             0 - Nothing
             1 - Go to sleep (doze)
diff --git a/core/res/res/values/symbols.xml b/core/res/res/values/symbols.xml
index 70f4f54b1ffe1..14707413c4dcd 100644
--- a/core/res/res/values/symbols.xml
+++ b/core/res/res/values/symbols.xml
@@ -382,6 +382,7 @@
   <java-symbol type="integer" name="config_extraFreeKbytesAbsolute" />
   <java-symbol type="integer" name="config_immersive_mode_confirmation_panic" />
   <java-symbol type="integer" name="config_longPressOnPowerBehavior" />
+  <java-symbol type="integer" name="config_longPressOnBackBehavior" />
   <java-symbol type="integer" name="config_lowMemoryKillerMinFreeKbytesAdjust" />
   <java-symbol type="integer" name="config_lowMemoryKillerMinFreeKbytesAbsolute" />
   <java-symbol type="integer" name="config_max_pan_devices" />
diff --git a/services/core/java/com/android/server/policy/PhoneWindowManager.java b/services/core/java/com/android/server/policy/PhoneWindowManager.java
index 76a93d49fd9c1..9af1304afc689 100644
--- a/services/core/java/com/android/server/policy/PhoneWindowManager.java
+++ b/services/core/java/com/android/server/policy/PhoneWindowManager.java
@@ -191,6 +191,9 @@ public class PhoneWindowManager implements WindowManagerPolicy {
     static final int LONG_PRESS_POWER_SHUT_OFF = 2;
     static final int LONG_PRESS_POWER_SHUT_OFF_NO_CONFIRM = 3;
 
+    static final int LONG_PRESS_BACK_NOTHING = 0;
+    static final int LONG_PRESS_BACK_GO_TO_VOICE_ASSIST = 1;
+
     static final int MULTI_PRESS_POWER_NOTHING = 0;
     static final int MULTI_PRESS_POWER_THEATER_MODE = 1;
     static final int MULTI_PRESS_POWER_BRIGHTNESS_BOOST = 2;
@@ -391,6 +394,7 @@ public class PhoneWindowManager implements WindowManagerPolicy {
     // handler thread.  We'll need to resolve this someday by teaching the input dispatcher
     // to hold wakelocks during dispatch and eliminating the critical path.
     volatile boolean mPowerKeyHandled;
+    volatile boolean mBackKeyHandled;
     volatile boolean mBeganFromNonInteractive;
     volatile int mPowerKeyPressCounter;
     volatile boolean mEndCallKeyHandled;
@@ -443,6 +447,7 @@ public class PhoneWindowManager implements WindowManagerPolicy {
     int mLongPressOnPowerBehavior;
     int mDoublePressOnPowerBehavior;
     int mTriplePressOnPowerBehavior;
+    int mLongPressOnBackBehavior;
     int mShortPressOnSleepBehavior;
     int mShortPressWindowBehavior;
     boolean mAwake;
@@ -699,6 +704,7 @@ public class PhoneWindowManager implements WindowManagerPolicy {
     private static final int MSG_UPDATE_DREAMING_SLEEP_TOKEN = 15;
     private static final int MSG_REQUEST_TRANSIENT_BARS = 16;
     private static final int MSG_REQUEST_TV_PICTURE_IN_PICTURE = 17;
+    private static final int MSG_BACK_LONG_PRESS = 18;
 
     private static final int MSG_REQUEST_TRANSIENT_BARS_ARG_STATUS = 0;
     private static final int MSG_REQUEST_TRANSIENT_BARS_ARG_NAVIGATION = 1;
@@ -763,6 +769,9 @@ public class PhoneWindowManager implements WindowManagerPolicy {
                 case MSG_REQUEST_TV_PICTURE_IN_PICTURE:
                     requestTvPictureInPictureInternal();
                     break;
+                case MSG_BACK_LONG_PRESS:
+                    backLongPress();
+                    break;
             }
         }
     }
@@ -1109,6 +1118,13 @@ public class PhoneWindowManager implements WindowManagerPolicy {
         }
     }
 
+    private void cancelPendingBackKeyAction() {
+        if (!mBackKeyHandled) {
+            mBackKeyHandled = true;
+            mHandler.removeMessages(MSG_BACK_LONG_PRESS);
+        }
+    }
+
     private void powerPress(long eventTime, boolean interactive, int count) {
         if (mScreenOnEarly && !mScreenOnFully) {
             Slog.i(TAG, "Suppressed redundant power key press while "
@@ -1216,6 +1232,19 @@ public class PhoneWindowManager implements WindowManagerPolicy {
         }
     }
 
+    private void backLongPress() {
+        mBackKeyHandled = true;
+
+        switch (mLongPressOnBackBehavior) {
+            case LONG_PRESS_BACK_NOTHING:
+                break;
+            case LONG_PRESS_BACK_GO_TO_VOICE_ASSIST:
+                Intent intent = new Intent(Intent.ACTION_VOICE_ASSIST);
+                startActivityAsUser(intent, UserHandle.CURRENT_OR_SELF);
+                break;
+        }
+    }
+
     private void sleepPress(long eventTime) {
         if (mShortPressOnSleepBehavior == SHORT_PRESS_SLEEP_GO_TO_SLEEP_AND_GO_HOME) {
             launchHomeFromHotKey(false /* awakenDreams */, true /*respectKeyguard*/);
@@ -1244,6 +1273,10 @@ public class PhoneWindowManager implements WindowManagerPolicy {
         return getResolvedLongPressOnPowerBehavior() != LONG_PRESS_POWER_NOTHING;
     }
 
+    private boolean hasLongPressOnBackBehavior() {
+        return mLongPressOnBackBehavior != LONG_PRESS_BACK_NOTHING;
+    }
+
     private void interceptScreenshotChord() {
         if (mScreenshotChordEnabled
                 && mScreenshotChordVolumeDownKeyTriggered && mScreenshotChordPowerKeyTriggered
@@ -1573,6 +1606,9 @@ public class PhoneWindowManager implements WindowManagerPolicy {
         mSupportLongPressPowerWhenNonInteractive = mContext.getResources().getBoolean(
                 com.android.internal.R.bool.config_supportLongPressPowerWhenNonInteractive);
 
+        mLongPressOnBackBehavior = mContext.getResources().getInteger(
+                com.android.internal.R.integer.config_longPressOnBackBehavior);
+
         mShortPressOnPowerBehavior = mContext.getResources().getInteger(
                 com.android.internal.R.integer.config_shortPressOnPowerBehavior);
         mLongPressOnPowerBehavior = mContext.getResources().getInteger(
@@ -5341,6 +5377,29 @@ public class PhoneWindowManager implements WindowManagerPolicy {
 
         // Handle special keys.
         switch (keyCode) {
+            case KeyEvent.KEYCODE_BACK: {
+                if (down) {
+                    mBackKeyHandled = false;
+                    if (hasLongPressOnBackBehavior()) {
+                        Message msg = mHandler.obtainMessage(MSG_BACK_LONG_PRESS);
+                        msg.setAsynchronous(true);
+                        mHandler.sendMessageDelayed(msg,
+                                ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());
+                    }
+                } else {
+                    boolean handled = mBackKeyHandled;
+
+                    // Reset back key state
+                    cancelPendingBackKeyAction();
+
+                    // Don't pass back press to app if we've already handled it
+                    if (handled) {
+                        result &= ~ACTION_PASS_TO_USER;
+                    }
+                }
+                break;
+            }
+
             case KeyEvent.KEYCODE_VOLUME_DOWN:
             case KeyEvent.KEYCODE_VOLUME_UP:
             case KeyEvent.KEYCODE_VOLUME_MUTE: {
@@ -7389,6 +7448,8 @@ public class PhoneWindowManager implements WindowManagerPolicy {
                 pw.print(" mLidNavigationAccessibility="); pw.print(mLidNavigationAccessibility);
                 pw.print(" mLidControlsScreenLock="); pw.println(mLidControlsScreenLock);
                 pw.print(" mLidControlsSleep="); pw.println(mLidControlsSleep);
+        pw.print(prefix);
+                pw.print(" mLongPressOnBackBehavior="); pw.println(mLongPressOnBackBehavior);
         pw.print(prefix);
                 pw.print("mShortPressOnPowerBehavior="); pw.print(mShortPressOnPowerBehavior);
                 pw.print(" mLongPressOnPowerBehavior="); pw.println(mLongPressOnPowerBehavior);