diff --git a/java/com/android/dialer/app/res/values/cm_strings.xml b/java/com/android/dialer/app/res/values/cm_strings.xml
index ba15b46..0ba0d50 100644
--- a/java/com/android/dialer/app/res/values/cm_strings.xml
+++ b/java/com/android/dialer/app/res/values/cm_strings.xml
@@ -18,6 +18,7 @@
 <resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
     <string name="incall_category_key" translatable="false">dialer_general_incall_category_key</string>
     <string name="incall_category_title">In-call</string>
+    <string name="incall_enable_dnd_title">Enable Do Not Disturb during calls</string>
     <string name="incall_vibrate_outgoing_key" translatable="false">incall_vibrate_outgoing</string>
     <string name="incall_vibrate_outgoing_title">Vibrate on answer</string>
     <string name="incall_vibrate_call_waiting_key" translatable="false">incall_vibrate_call_waiting</string>
@@ -27,4 +28,7 @@
     <string name="incall_vibrate_45_key" translatable="false">incall_vibrate_45secs</string>
     <string name="incall_vibrate_45_title">Vibrate every minute</string>
     <string name="incall_vibrate_45_summary">Vibrates at the 45 second mark of every minute during outgoing calls</string>
+    <string name="incall_dnd_dialog_message">In order to enable Do Not Disturb, the Phone app needs to be granted the permission to control the Do Not Disturb status.\nPlease allow it.</string>
+    <string name="allow">Allow</string>
+    <string name="deny">Deny</string>
 </resources>
diff --git a/java/com/android/dialer/app/res/xml/sound_settings.xml b/java/com/android/dialer/app/res/xml/sound_settings.xml
index e26e51a..4da5c15 100644
--- a/java/com/android/dialer/app/res/xml/sound_settings.xml
+++ b/java/com/android/dialer/app/res/xml/sound_settings.xml
@@ -48,6 +48,11 @@
     android:title="@string/incall_category_title">
 
     <SwitchPreference
+        android:defaultValue="false"
+        android:key="incall_enable_dnd"
+        android:title="@string/incall_enable_dnd_title"/>
+
+    <SwitchPreference
       android:key="@string/incall_vibrate_outgoing_key"
       android:title="@string/incall_vibrate_outgoing_title" />
 
diff --git a/java/com/android/dialer/app/settings/SoundSettingsFragment.java b/java/com/android/dialer/app/settings/SoundSettingsFragment.java
index 3c254cc..d9f24ab 100644
--- a/java/com/android/dialer/app/settings/SoundSettingsFragment.java
+++ b/java/com/android/dialer/app/settings/SoundSettingsFragment.java
@@ -16,7 +16,11 @@
 
 package com.android.dialer.app.settings;
 
+import android.app.AlertDialog;
+import android.app.NotificationManager;
 import android.content.Context;
+import android.content.DialogInterface;
+import android.content.Intent;
 import android.media.RingtoneManager;
 import android.os.Build;
 import android.os.Bundle;
@@ -70,6 +74,9 @@
   private SwitchPreference vibrateWhenRinging;
   private SwitchPreference playDtmfTone;
   private ListPreference dtmfToneLength;
+  private SwitchPreference enableDndInCall;
+
+  private NotificationManager notificationManager;
 
   @Override
   public Context getContext() {
@@ -92,6 +99,7 @@
     dtmfToneLength =
         (ListPreference)
             findPreference(context.getString(R.string.dtmf_tone_length_preference_key));
+    enableDndInCall = (SwitchPreference) findPreference("incall_enable_dnd");
 
     if (hasVibrator()) {
       vibrateWhenRinging.setOnPreferenceChangeListener(this);
@@ -116,6 +124,8 @@
     playDtmfTone.setOnPreferenceChangeListener(this);
     playDtmfTone.setChecked(shouldPlayDtmfTone());
 
+    enableDndInCall.setOnPreferenceChangeListener(this);
+
     TelephonyManager telephonyManager =
         (TelephonyManager) getActivity().getSystemService(Context.TELEPHONY_SERVICE);
     if (telephonyManager.canChangeDtmfToneLength()
@@ -130,6 +140,7 @@
       getPreferenceScreen().removePreference(dtmfToneLength);
       dtmfToneLength = null;
     }
+    notificationManager = context.getSystemService(NotificationManager.class);
   }
 
   @Override
@@ -178,6 +189,30 @@
       int index = dtmfToneLength.findIndexOfValue((String) objValue);
       Settings.System.putInt(
           getActivity().getContentResolver(), Settings.System.DTMF_TONE_TYPE_WHEN_DIALING, index);
+    } else if (preference == enableDndInCall) {
+      boolean newValue = (Boolean) objValue;
+      if (newValue && !notificationManager.isNotificationPolicyAccessGranted()) {
+        new AlertDialog.Builder(getContext())
+            .setMessage(R.string.incall_dnd_dialog_message)
+            .setPositiveButton(R.string.allow, new DialogInterface.OnClickListener() {
+              @Override
+              public void onClick(DialogInterface dialog, int which) {
+                dialog.dismiss();
+                Intent intent = new Intent(android.provider.Settings.ACTION_NOTIFICATION_POLICY_ACCESS_SETTINGS);
+                startActivity(intent);
+              }
+            })
+            .setNegativeButton(R.string.deny, new DialogInterface.OnClickListener() {
+              @Override
+              public void onClick(DialogInterface dialog, int which) {
+                dialog.dismiss();
+              }
+            })
+            .show();
+
+        // At this time, it is unknown whether the user granted the permission
+        return false;
+      }
     }
     return true;
   }
diff --git a/java/com/android/incallui/AndroidManifest.xml b/java/com/android/incallui/AndroidManifest.xml
index 4cb6001..8e69c0d 100644
--- a/java/com/android/incallui/AndroidManifest.xml
+++ b/java/com/android/incallui/AndroidManifest.xml
@@ -46,6 +46,9 @@
   <!-- Set audio selector window type TYPE_APPLICATION_OVERLAY -->
   <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
 
+  <!-- Required when the "Enable Do Not Disturb during call" setting is enabled -->
+  <uses-permission android:name="android.permission.ACCESS_NOTIFICATION_POLICY" />
+
   <!-- Set android:taskAffinity="com.android.incallui" for all activities to ensure proper
   navigation. Otherwise system could bring up MainActivity instead, e.g. when user unmerge a
   call.
diff --git a/java/com/android/incallui/InCallDndHandler.java b/java/com/android/incallui/InCallDndHandler.java
new file mode 100644
index 0000000..4ab3e84
--- /dev/null
+++ b/java/com/android/incallui/InCallDndHandler.java
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2018 The LineageOS 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.incallui;
+
+import android.app.NotificationManager;
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.preference.PreferenceManager;
+
+import com.android.incallui.call.CallList;
+import com.android.incallui.call.DialerCall;
+import com.android.incallui.call.state.DialerCallState;
+import com.android.incallui.InCallPresenter.InCallState;
+
+public class InCallDndHandler implements InCallPresenter.InCallStateListener {
+
+  private static final String KEY_ENABLE_DND = "incall_enable_dnd";
+
+  private SharedPreferences prefs;
+  private DialerCall activeCall;
+  private NotificationManager notificationManager;
+  private int userSelectedDndMode;
+
+  public InCallDndHandler(Context context) {
+    prefs = PreferenceManager.getDefaultSharedPreferences(context);
+    notificationManager = context.getSystemService(NotificationManager.class);
+
+    // Save the user's Do Not Disturb mode so that it can be restored when the call ends
+    userSelectedDndMode = notificationManager.getCurrentInterruptionFilter();
+  }
+
+  @Override
+  public void onStateChange(InCallState oldState, InCallState newState, CallList callList) {
+    DialerCall activeCall = callList.getActiveCall();
+
+    if (activeCall != null && this.activeCall == null) {
+      Log.d(this, "Transition to active call " + activeCall);
+      handleDndState(activeCall);
+      this.activeCall = activeCall;
+    } else if (activeCall == null && this.activeCall != null) {
+      Log.d(this, "Transition from active call " + this.activeCall);
+      handleDndState(this.activeCall);
+      this.activeCall = null;
+    }
+  }
+
+  private void handleDndState(DialerCall call) {
+    if (!prefs.getBoolean(KEY_ENABLE_DND, false)) {
+      return;
+    }
+    if (DialerCallState.isConnectingOrConnected(call.getState())) {
+      Log.d(this, "Enabling Do Not Disturb mode");
+      setDoNotDisturbMode(NotificationManager.INTERRUPTION_FILTER_NONE);
+    } else {
+      Log.d(this, "Restoring previous Do Not Disturb mode");
+      setDoNotDisturbMode(userSelectedDndMode);
+    }
+  }
+
+  private void setDoNotDisturbMode(int newMode) {
+    if (notificationManager.isNotificationPolicyAccessGranted()) {
+      notificationManager.setInterruptionFilter(newMode);
+    } else {
+      Log.e(this, "Failed to set Do Not Disturb mode " + newMode + " due to lack of permissions");
+    }
+  }
+}
diff --git a/java/com/android/incallui/InCallPresenter.java b/java/com/android/incallui/InCallPresenter.java
index aecf891..83ec9ab 100644
--- a/java/com/android/incallui/InCallPresenter.java
+++ b/java/com/android/incallui/InCallPresenter.java
@@ -128,6 +128,7 @@
   private StatusBarNotifier statusBarNotifier;
   private ExternalCallNotifier externalCallNotifier;
   private InCallVibrationHandler vibrationHandler;
+  private InCallDndHandler dndHandler;
   private ContactInfoCache contactInfoCache;
   private Context context;
   private final OnCheckBlockedListener onCheckBlockedListener =
@@ -365,6 +366,9 @@
     vibrationHandler = new InCallVibrationHandler(context);
     addListener(vibrationHandler);
 
+    dndHandler = new InCallDndHandler(context);
+    addListener(dndHandler);
+
     this.proximitySensor = proximitySensor;
     addListener(this.proximitySensor);
 
@@ -1657,6 +1661,11 @@
       }
       vibrationHandler = null;
 
+      if (dndHandler != null) {
+        removeListener(dndHandler);
+      }
+      dndHandler = null;
+
       if (callList != null) {
         callList.removeListener(this);
         callList.removeListener(spamCallListListener);