diff --git a/res/values/strings.xml b/res/values/strings.xml
index e65806bb3d6..87858e57aa6 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -12804,6 +12804,12 @@
     <!-- Power menu setting privacy no secure screen lock set [CHAR_LIMIT=NONE] -->
     <string name="power_menu_privacy_not_secure">To use, first set a screen lock</string>
 
+    <!-- Power menu setting use long press power to invoke assistant. [CHAR_LIMIT=NONE] -->
+    <string name="power_menu_long_press_for_assist">Hold for Assistant</string>
+
+    <!-- Power menu setting use log press power to invoke assistant summary. [CHAR_LIMIT=NONE] -->
+    <string name="power_menu_long_press_for_assist_summary">Trigger the Assistant by holding the power button</string>
+
     <!-- Device controls toggle name [CHAR LIMIT=60] -->
     <string name="device_controls_setting_toggle">Show device controls</string>
 
diff --git a/res/xml/power_menu_settings.xml b/res/xml/power_menu_settings.xml
index c7fba713183..bfe9c20679b 100644
--- a/res/xml/power_menu_settings.xml
+++ b/res/xml/power_menu_settings.xml
@@ -20,6 +20,13 @@
     xmlns:settings="http://schemas.android.com/apk/res-auto"
     android:title="@string/power_menu_setting_name">
 
+    <SwitchPreference
+        android:key="gesture_power_menu_long_press_for_assist"
+        android:title="@string/power_menu_long_press_for_assist"
+        android:summary="@string/power_menu_long_press_for_assist_summary"
+        settings:controller="com.android.settings.gestures.LongPressPowerButtonPreferenceController"
+        />
+
     <Preference
         android:key="gesture_global_actions_panel_summary"
         android:title="@string/cards_passes_sentence"
diff --git a/src/com/android/settings/gestures/LongPressPowerButtonPreferenceController.java b/src/com/android/settings/gestures/LongPressPowerButtonPreferenceController.java
new file mode 100644
index 00000000000..7a456023614
--- /dev/null
+++ b/src/com/android/settings/gestures/LongPressPowerButtonPreferenceController.java
@@ -0,0 +1,188 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.gestures;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.content.pm.PackageManager;
+import android.database.ContentObserver;
+import android.net.Uri;
+import android.os.Handler;
+import android.os.Looper;
+import android.provider.Settings;
+
+import androidx.annotation.Nullable;
+import androidx.lifecycle.Lifecycle;
+import androidx.lifecycle.LifecycleObserver;
+import androidx.lifecycle.OnLifecycleEvent;
+import androidx.preference.Preference;
+import androidx.preference.PreferenceScreen;
+
+import com.android.internal.R;
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.settings.core.TogglePreferenceController;
+
+/**
+ * Configures the behaviour of long press power button action.
+ */
+public class LongPressPowerButtonPreferenceController extends TogglePreferenceController implements
+        LifecycleObserver {
+
+    private static final String POWER_BUTTON_LONG_PRESS_SETTING =
+            Settings.Global.POWER_BUTTON_LONG_PRESS;
+    private static final Uri POWER_BUTTON_LONG_PRESS_SETTING_URI =
+            Settings.Global.getUriFor(POWER_BUTTON_LONG_PRESS_SETTING);
+
+    // Used for fallback to global actions if necessary.
+    @VisibleForTesting
+    static final String CARDS_AVAILABLE_KEY =
+            Settings.Secure.GLOBAL_ACTIONS_PANEL_AVAILABLE;
+    @VisibleForTesting
+    static final String CARDS_ENABLED_KEY = Settings.Secure.GLOBAL_ACTIONS_PANEL_ENABLED;
+
+    /**
+     * Value used for long press power button behaviour when Assist setting is enabled.
+     *
+     * {@link com.android.server.policy.PhoneWindowManager#LONG_PRESS_POWER_GLOBAL_ACTIONS} for
+     * source of the value.
+     */
+    @VisibleForTesting
+    static final int LONG_PRESS_POWER_GLOBAL_ACTIONS = 1;
+    @VisibleForTesting
+    static final int LONG_PRESS_POWER_SHUT_OFF = 2;
+    @VisibleForTesting
+    static final int LONG_PRESS_POWER_ASSISTANT_VALUE = 5; // Settings.Secure.ASSISTANT
+
+    /**
+     * Value used for long press power button behaviour when the Assist setting is disabled.
+     *
+     * If this value matches Assist setting, then it falls back to Global Actions panel or
+     * power menu, depending on their respective settings.
+     */
+    private static final int POWER_BUTTON_LONG_PRESS_DEFAULT_VALUE_RESOURCE =
+            R.integer.config_longPressOnPowerBehavior;
+
+    @Nullable
+    private SettingObserver mSettingsObserver;
+
+    public LongPressPowerButtonPreferenceController(Context context, String key) {
+        super(context, key);
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        mSettingsObserver = new SettingObserver(screen.findPreference(getPreferenceKey()));
+    }
+
+    /**
+     * Called when the settings pages resumes.
+     */
+    @OnLifecycleEvent(Lifecycle.Event.ON_RESUME)
+    public void onResume() {
+        if (mSettingsObserver != null) {
+            mSettingsObserver.register();
+        }
+    }
+
+    /**
+     * Called when the settings page pauses.
+     */
+    @OnLifecycleEvent(Lifecycle.Event.ON_PAUSE)
+    public void onPause() {
+        if (mSettingsObserver != null) {
+            mSettingsObserver.unregister();
+        }
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        final boolean enabled = mContext.getResources().getBoolean(
+                com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable);
+        return enabled ? AVAILABLE : UNSUPPORTED_ON_DEVICE;
+    }
+
+    @Override
+    public boolean isChecked() {
+        final int powerButtonValue = Settings.Global.getInt(mContext.getContentResolver(),
+                POWER_BUTTON_LONG_PRESS_SETTING,
+                mContext.getResources().getInteger(POWER_BUTTON_LONG_PRESS_DEFAULT_VALUE_RESOURCE));
+        return powerButtonValue == LONG_PRESS_POWER_ASSISTANT_VALUE;
+    }
+
+    @Override
+    public boolean setChecked(boolean isChecked) {
+        if (isChecked) {
+            return Settings.Global.putInt(mContext.getContentResolver(),
+                    POWER_BUTTON_LONG_PRESS_SETTING, LONG_PRESS_POWER_ASSISTANT_VALUE);
+        }
+
+        // We need to determine the right disabled value - we set it to device default
+        // if it's different than Assist, otherwise we fallback to either global actions or power
+        //menu.
+        final int defaultPowerButtonValue = mContext.getResources().getInteger(
+                POWER_BUTTON_LONG_PRESS_DEFAULT_VALUE_RESOURCE);
+        if (defaultPowerButtonValue == LONG_PRESS_POWER_ASSISTANT_VALUE) {
+            final int fallbackValue = isCardsOrControlsAvailable() ? LONG_PRESS_POWER_GLOBAL_ACTIONS
+                    : LONG_PRESS_POWER_SHUT_OFF;
+            return Settings.Global.putInt(mContext.getContentResolver(),
+                    POWER_BUTTON_LONG_PRESS_SETTING, fallbackValue);
+        }
+
+        return Settings.Global.putInt(mContext.getContentResolver(),
+                POWER_BUTTON_LONG_PRESS_SETTING, defaultPowerButtonValue);
+    }
+
+    /**
+     * Returns true if the global actions menu on power button click is enabled via any of the
+     * content options.
+     */
+    private boolean isCardsOrControlsAvailable() {
+        final ContentResolver resolver = mContext.getContentResolver();
+        final boolean cardsAvailable = Settings.Secure.getInt(resolver, CARDS_AVAILABLE_KEY, 0)
+                != 0;
+        final boolean controlsAvailable = mContext.getPackageManager().hasSystemFeature(
+                PackageManager.FEATURE_CONTROLS);
+        return cardsAvailable || controlsAvailable;
+    }
+
+    private final class SettingObserver extends ContentObserver {
+
+        private final Preference mPreference;
+
+        SettingObserver(Preference preference) {
+            super(new Handler(Looper.getMainLooper()));
+            mPreference = preference;
+        }
+
+        public void register() {
+            final ContentResolver cr = mContext.getContentResolver();
+            cr.registerContentObserver(POWER_BUTTON_LONG_PRESS_SETTING_URI, false, this);
+        }
+
+        public void unregister() {
+            final ContentResolver cr = mContext.getContentResolver();
+            cr.unregisterContentObserver(this);
+        }
+
+        @Override
+        public void onChange(boolean selfChange) {
+            updateState(mPreference);
+        }
+    }
+
+}
diff --git a/src/com/android/settings/gestures/PowerMenuPreferenceController.java b/src/com/android/settings/gestures/PowerMenuPreferenceController.java
index 6ef583b7037..b11ba65c43c 100644
--- a/src/com/android/settings/gestures/PowerMenuPreferenceController.java
+++ b/src/com/android/settings/gestures/PowerMenuPreferenceController.java
@@ -57,7 +57,8 @@ public class PowerMenuPreferenceController extends BasePreferenceController {
 
     @Override
     public int getAvailabilityStatus() {
-        return isCardsAvailable() || isControlsAvailable() ? AVAILABLE : CONDITIONALLY_UNAVAILABLE;
+        return isCardsAvailable() || isControlsAvailable() || isAssistInvocationAvailable()
+                ? AVAILABLE : CONDITIONALLY_UNAVAILABLE;
     }
 
     private boolean isControlsAvailable() {
@@ -68,4 +69,9 @@ public class PowerMenuPreferenceController extends BasePreferenceController {
         return Settings.Secure.getInt(mContext.getContentResolver(),
                 CARDS_AVAILABLE_SETTING, 0) == 1;
     }
+
+    private boolean isAssistInvocationAvailable() {
+        return mContext.getResources().getBoolean(
+                com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable);
+    }
 }
diff --git a/tests/robotests/src/com/android/settings/gestures/LongPressPowerButtonPreferenceControllerTest.java b/tests/robotests/src/com/android/settings/gestures/LongPressPowerButtonPreferenceControllerTest.java
new file mode 100644
index 00000000000..de58c994fb4
--- /dev/null
+++ b/tests/robotests/src/com/android/settings/gestures/LongPressPowerButtonPreferenceControllerTest.java
@@ -0,0 +1,129 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.gestures;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.when;
+
+import android.app.Application;
+import android.content.res.Resources;
+import android.provider.Settings;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+
+@RunWith(RobolectricTestRunner.class)
+public class LongPressPowerButtonPreferenceControllerTest {
+
+    private static final String KEY_LONG_PRESS_POWER_BUTTON =
+            "gesture_power_menu_long_press_for_assist";
+
+    private Application mContext;
+    private Resources mResources;
+    private LongPressPowerButtonPreferenceController mController;
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+        mContext = spy(RuntimeEnvironment.application);
+        mResources = mock(Resources.class);
+        when(mContext.getResources()).thenReturn(mResources);
+        when(mResources.getBoolean(
+                com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable))
+                .thenReturn(true);
+        mController = new LongPressPowerButtonPreferenceController(mContext,
+                KEY_LONG_PRESS_POWER_BUTTON);
+    }
+
+    @Test
+    public void isAvailable_configIsTrue_shouldReturnTrue() {
+        when(mResources.getBoolean(
+                com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable))
+                .thenReturn(true);
+
+        assertThat(mController.isAvailable()).isTrue();
+    }
+
+    @Test
+    public void isAvailable_configIsFalse_shouldReturnFalse() {
+        when(mResources.getBoolean(
+                com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable))
+                .thenReturn(false);
+
+        assertThat(mController.isAvailable()).isFalse();
+    }
+
+    @Test
+    public void preferenceChecked_longPressPowerSettingSetToAssistant() {
+        mController.onPreferenceChange(null, true);
+
+        assertThat(Settings.Global.getInt(mContext.getContentResolver(),
+                Settings.Global.POWER_BUTTON_LONG_PRESS, -1)).isEqualTo(
+                LongPressPowerButtonPreferenceController.LONG_PRESS_POWER_ASSISTANT_VALUE);
+    }
+
+    @Test
+    public void preferenceUnchecked_longPressPowerSettingSetToDefaultValue() {
+        // Value out of range chosen deliberately.
+        when(mResources.getInteger(
+                com.android.internal.R.integer.config_longPressOnPowerBehavior))
+                .thenReturn(8);
+
+        mController.onPreferenceChange(null, false);
+        assertThat(Settings.Global.getInt(mContext.getContentResolver(),
+                Settings.Global.POWER_BUTTON_LONG_PRESS, -1)).isEqualTo(8);
+    }
+
+    @Test
+    public void preferenceUnchecked_assistDefault_setShutOff() {
+        // Value out of range chosen deliberately.
+        when(mResources.getInteger(
+                com.android.internal.R.integer.config_longPressOnPowerBehavior))
+                .thenReturn(
+                        LongPressPowerButtonPreferenceController.LONG_PRESS_POWER_ASSISTANT_VALUE);
+
+        mController.onPreferenceChange(null, false);
+        assertThat(Settings.Global.getInt(mContext.getContentResolver(),
+                Settings.Global.POWER_BUTTON_LONG_PRESS, -1)).isEqualTo(
+                LongPressPowerButtonPreferenceController.LONG_PRESS_POWER_SHUT_OFF);
+    }
+
+    @Test
+    public void preferenceUnchecked_assistDefaultGlobalActionsEnabled_setGlobalActions() {
+        // Value out of range chosen deliberately.
+        when(mResources.getInteger(
+                com.android.internal.R.integer.config_longPressOnPowerBehavior))
+                .thenReturn(
+                        LongPressPowerButtonPreferenceController.LONG_PRESS_POWER_ASSISTANT_VALUE);
+        Settings.Secure.putInt(mContext.getContentResolver(),
+                LongPressPowerButtonPreferenceController.CARDS_AVAILABLE_KEY, 1);
+        Settings.Secure.putInt(mContext.getContentResolver(),
+                LongPressPowerButtonPreferenceController.CARDS_ENABLED_KEY, 1);
+
+        mController.onPreferenceChange(null, false);
+        assertThat(Settings.Global.getInt(mContext.getContentResolver(),
+                Settings.Global.POWER_BUTTON_LONG_PRESS, -1)).isEqualTo(
+                LongPressPowerButtonPreferenceController.LONG_PRESS_POWER_GLOBAL_ACTIONS);
+    }
+}
diff --git a/tests/robotests/src/com/android/settings/gestures/PowerMenuPreferenceControllerTest.java b/tests/robotests/src/com/android/settings/gestures/PowerMenuPreferenceControllerTest.java
index 570a68040f7..f8d81f24bc9 100644
--- a/tests/robotests/src/com/android/settings/gestures/PowerMenuPreferenceControllerTest.java
+++ b/tests/robotests/src/com/android/settings/gestures/PowerMenuPreferenceControllerTest.java
@@ -18,8 +18,13 @@ package com.android.settings.gestures;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.when;
+
 import android.content.Context;
 import android.content.pm.PackageManager;
+import android.content.res.Resources;
 import android.provider.Settings;
 
 import com.android.settings.core.BasePreferenceController;
@@ -35,6 +40,7 @@ import org.robolectric.shadows.ShadowPackageManager;
 @RunWith(RobolectricTestRunner.class)
 public class PowerMenuPreferenceControllerTest {
     private Context mContext;
+    private Resources mResources;
     private PowerMenuPreferenceController mController;
     private ShadowPackageManager mShadowPackageManager;
 
@@ -44,17 +50,26 @@ public class PowerMenuPreferenceControllerTest {
     private static final String CARDS_ENABLED = Settings.Secure.GLOBAL_ACTIONS_PANEL_ENABLED;
     private static final String CARDS_AVAILABLE = Settings.Secure.GLOBAL_ACTIONS_PANEL_AVAILABLE;
 
+
     @Before
     public void setUp() {
-        mContext = RuntimeEnvironment.application;
+        mContext = spy(RuntimeEnvironment.application);
+        mResources = mock(Resources.class);
+        when(mResources.getBoolean(
+            com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable))
+                .thenReturn(true);
+        when(mContext.getResources()).thenReturn(mResources);
         mShadowPackageManager = Shadows.shadowOf(mContext.getPackageManager());
         mController = new PowerMenuPreferenceController(mContext, KEY_GESTURE_POWER_MENU);
     }
 
     @Test
-    public void getAvailabilityStatus_bothAvailable_available() {
+    public void getAvailabilityStatus_allAvailable_available() {
         Settings.Secure.putInt(mContext.getContentResolver(), CARDS_AVAILABLE, 1);
         mShadowPackageManager.setSystemFeature(CONTROLS_FEATURE, true);
+        when(mResources.getBoolean(
+                com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable))
+                    .thenReturn(true);
 
         assertThat(mController.getAvailabilityStatus()).isEqualTo(
                 BasePreferenceController.AVAILABLE);
@@ -64,6 +79,9 @@ public class PowerMenuPreferenceControllerTest {
     public void getAvailabilityStatus_onlyCardsAvailable_available() {
         Settings.Secure.putInt(mContext.getContentResolver(), CARDS_AVAILABLE, 1);
         mShadowPackageManager.setSystemFeature(CONTROLS_FEATURE, false);
+        when(mResources.getBoolean(
+                com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable))
+                    .thenReturn(false);
 
         assertThat(mController.getAvailabilityStatus()).isEqualTo(
                 BasePreferenceController.AVAILABLE);
@@ -73,15 +91,69 @@ public class PowerMenuPreferenceControllerTest {
     public void getAvailabilityStatus_onlyControlsAvailable_available() {
         Settings.Secure.putInt(mContext.getContentResolver(), CARDS_AVAILABLE, 0);
         mShadowPackageManager.setSystemFeature(CONTROLS_FEATURE, true);
+        when(mResources.getBoolean(
+                com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable))
+                    .thenReturn(false);
 
         assertThat(mController.getAvailabilityStatus()).isEqualTo(
                 BasePreferenceController.AVAILABLE);
     }
 
     @Test
-    public void getAvailabilityStatus_bothUnavailable_unavailable() {
+    public void getAvailabilityStatus_controlsAndCardsAvailable_available() {
+        Settings.Secure.putInt(mContext.getContentResolver(), CARDS_AVAILABLE, 1);
+        mShadowPackageManager.setSystemFeature(CONTROLS_FEATURE, true);
+        when(mResources.getBoolean(
+                com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable))
+                    .thenReturn(false);
+
+        assertThat(mController.getAvailabilityStatus()).isEqualTo(
+                BasePreferenceController.AVAILABLE);
+    }
+
+    @Test
+    public void getAvailabilityStatus_controlsAndAssistAvailable_available() {
+        Settings.Secure.putInt(mContext.getContentResolver(), CARDS_AVAILABLE, 0);
+        mShadowPackageManager.setSystemFeature(CONTROLS_FEATURE, true);
+        when(mResources.getBoolean(
+                com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable))
+                    .thenReturn(true);
+
+        assertThat(mController.getAvailabilityStatus()).isEqualTo(
+                BasePreferenceController.AVAILABLE);
+    }
+
+    @Test
+    public void getAvailabilityStatus_cardsAndAssistAvailable_available() {
+        Settings.Secure.putInt(mContext.getContentResolver(), CARDS_AVAILABLE, 1);
+        mShadowPackageManager.setSystemFeature(CONTROLS_FEATURE, false);
+        when(mResources.getBoolean(
+                com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable))
+                    .thenReturn(true);
+
+        assertThat(mController.getAvailabilityStatus()).isEqualTo(
+                BasePreferenceController.AVAILABLE);
+    }
+
+    @Test
+    public void getAvailabilityStatus_onlyAssistAvailable_available() {
         Settings.Secure.putInt(mContext.getContentResolver(), CARDS_AVAILABLE, 0);
         mShadowPackageManager.setSystemFeature(CONTROLS_FEATURE, false);
+        when(mResources.getBoolean(
+                com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable))
+                    .thenReturn(true);
+
+        assertThat(mController.getAvailabilityStatus()).isEqualTo(
+                BasePreferenceController.AVAILABLE);
+    }
+
+    @Test
+    public void getAvailabilityStatus_allUnavailable_unavailable() {
+        Settings.Secure.putInt(mContext.getContentResolver(), CARDS_AVAILABLE, 0);
+        mShadowPackageManager.setSystemFeature(CONTROLS_FEATURE, false);
+        when(mResources.getBoolean(
+                com.android.internal.R.bool.config_longPressOnPowerForAssistantSettingAvailable))
+                    .thenReturn(true);
 
         assertThat(mController.getAvailabilityStatus()).isEqualTo(
                 BasePreferenceController.CONDITIONALLY_UNAVAILABLE);