diff --git a/browser/base/content/browser.css b/browser/base/content/browser.css
index 799fc51696ab..926700fcfade 100644
--- a/browser/base/content/browser.css
+++ b/browser/base/content/browser.css
@@ -494,6 +494,27 @@ toolbar:not(#TabsToolbar) > #personal-bookmarks {
   -moz-binding: url(chrome://browser/content/urlbarBindings.xml#urlbar);
 }
 
+/*
+ * Display visual cue that browser is under remote control by Marionette.
+ * This is to help users visually distinguish a user agent session that
+ * is under remote control from those used for normal browsing sessions.
+ *
+ * Attribute is controlled by browser.js:/gRemoteControl.
+ */
+#main-window[remotecontrol] #urlbar {
+  background: repeating-linear-gradient(
+    -45deg,
+    transparent,
+    transparent 25px,
+    rgba(255,255,255,.3) 25px,
+    rgba(255,255,255,.3) 50px);
+  background-color: rgba(255,170,68,.8);
+  color: black;
+}
+#main-window[remotecontrol] #urlbar #identity-box {
+  background: white;
+}
+
 /* Fade out URL on overflow */
 html|input.urlbar-input[textoverflow]:not([focused]) {
   /* Don't need to worry about RTL here since we use direction:ltr for the
diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index 7c17833c3c13..06959b2a9f50 100755
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -33,7 +33,8 @@ XPCOMUtils.defineLazyModuleGetter(this, "Preferences",
           Social:false, TabCrashHandler:false, Task:false, TelemetryStopwatch:false,
           Translation:false, UITour:false, UpdateUtils:false, Weave:false,
           WebNavigationFrames: false, fxAccounts:false, gDevTools:false,
-          gDevToolsBrowser:false, webrtcUI:false, FullZoomUI:false
+          gDevToolsBrowser:false, webrtcUI:false, FullZoomUI:false,
+          Marionette:false,
  */
 
 /**
@@ -106,9 +107,10 @@ if (AppConstants.MOZ_CRASHREPORTER) {
  */
 [
   ["Favicons", "@mozilla.org/browser/favicon-service;1", "mozIAsyncFavicons"],
-  ["WindowsUIUtils", "@mozilla.org/windows-ui-utils;1", "nsIWindowsUIUtils"],
   ["gAboutNewTabService", "@mozilla.org/browser/aboutnewtab-service;1", "nsIAboutNewTabService"],
   ["gDNSService", "@mozilla.org/network/dns-service;1", "nsIDNSService"],
+  ["Marionette", "@mozilla.org/remote/marionette;1", "nsIMarionette"],
+  ["WindowsUIUtils", "@mozilla.org/windows-ui-utils;1", "nsIWindowsUIUtils"],
 ].forEach(([name, cc, ci]) => XPCOMUtils.defineLazyServiceGetter(this, name, cc, ci));
 
 if (AppConstants.MOZ_CRASHREPORTER) {
@@ -1255,6 +1257,8 @@ var gBrowserInit = {
 
     ToolbarIconColor.init();
 
+    gRemoteControl.updateVisualCue(Marionette.running);
+
     // Wait until chrome is painted before executing code not critical to making the window visible
     this._boundDelayedStartup = this._delayedStartup.bind(this);
     window.addEventListener("MozAfterPaint", this._boundDelayedStartup);
@@ -1393,6 +1397,7 @@ var gBrowserInit = {
     setTimeout(function() { SafeBrowsing.init(); }, 2000);
 
     Services.obs.addObserver(gIdentityHandler, "perm-changed");
+    Services.obs.addObserver(gRemoteControl, "remote-active");
     Services.obs.addObserver(gSessionHistoryObserver, "browser:purge-session-history");
     Services.obs.addObserver(gStoragePressureObserver, "QuotaManager::StoragePressure");
     Services.obs.addObserver(gXPInstallObserver, "addon-install-disabled");
@@ -1713,6 +1718,7 @@ var gBrowserInit = {
       FullZoom.destroy();
 
       Services.obs.removeObserver(gIdentityHandler, "perm-changed");
+      Services.obs.removeObserver(gRemoteControl, "remote-active");
       Services.obs.removeObserver(gSessionHistoryObserver, "browser:purge-session-history");
       Services.obs.removeObserver(gStoragePressureObserver, "QuotaManager::StoragePressure");
       Services.obs.removeObserver(gXPInstallObserver, "addon-install-disabled");
@@ -7817,7 +7823,6 @@ var gIdentityHandler = {
   }
 };
 
-
 var gPageActionButton = {
   get button() {
     delete this.button;
@@ -7861,6 +7866,25 @@ var gPageActionButton = {
   },
 };
 
+/**
+ * Fired on the "marionette-remote-control" system notification,
+ * indicating if the browser session is under remote control.
+ */
+const gRemoteControl = {
+  observe(subject, topic, data) {
+    gRemoteControl.updateVisualCue(data);
+  },
+
+  updateVisualCue(enabled) {
+    const mainWindow = document.documentElement;
+    if (enabled) {
+      mainWindow.setAttribute("remotecontrol", "true");
+    } else {
+      mainWindow.removeAttribute("remotecontrol");
+    }
+  },
+};
+
 function getNotificationBox(aWindow) {
   var foundBrowser = gBrowser.getBrowserForDocument(aWindow.document);
   if (foundBrowser)
diff --git a/browser/base/content/browser.xul b/browser/base/content/browser.xul
index da2ffd2e9f38..ee0e8d07ca2a 100644
--- a/browser/base/content/browser.xul
+++ b/browser/base/content/browser.xul
@@ -846,6 +846,8 @@
                          tooltiptext="&urlbar.persistentStorageNotificationAnchor.tooltip;"/>
                 </box>
                 <image id="connection-icon"/>
+                <image id="remote-control-icon"
+                       tooltiptext="&urlbar.remoteControlNotificationAnchor.tooltip;"/>
                 <hbox id="identity-icon-labels">
                   <label id="identity-icon-label" class="plain" flex="1"/>
                   <label id="identity-icon-country-label" class="plain"/>
diff --git a/browser/locales/en-US/chrome/browser/browser.dtd b/browser/locales/en-US/chrome/browser/browser.dtd
index 9c4db829ff77..1cfaae2275b7 100644
--- a/browser/locales/en-US/chrome/browser/browser.dtd
+++ b/browser/locales/en-US/chrome/browser/browser.dtd
@@ -214,6 +214,7 @@ These should match what Safari and other Apple applications use on OS X Lion. --
 <!ENTITY urlbar.pluginsNotificationAnchor.tooltip         "Manage plug-in use">
 <!ENTITY urlbar.webNotificationAnchor.tooltip             "Change whether you can receive notifications from the site">
 <!ENTITY urlbar.persistentStorageNotificationAnchor.tooltip     "Store data in Persistent Storage">
+<!ENTITY urlbar.remoteControlNotificationAnchor.tooltip   "Browser is under remote control">
 
 <!ENTITY urlbar.webRTCShareDevicesNotificationAnchor.tooltip      "Manage sharing your camera and/or microphone with the site">
 <!ENTITY urlbar.webRTCShareMicrophoneNotificationAnchor.tooltip   "Manage sharing your microphone with the site">
diff --git a/browser/themes/shared/identity-block/identity-block.inc.css b/browser/themes/shared/identity-block/identity-block.inc.css
index 9ca0bc589ed5..8b92f5c3562e 100644
--- a/browser/themes/shared/identity-block/identity-block.inc.css
+++ b/browser/themes/shared/identity-block/identity-block.inc.css
@@ -164,3 +164,13 @@
   visibility: collapse;
 }
 
+
+/* REMOTE CONTROL ICON */
+
+#main-window[remotecontrol] #remote-control-icon {
+  list-style-image: url(chrome://browser/content/robot.ico);
+  visibility: visible;
+  width: 16px;
+  height: 16px;
+  margin-inline-start: 2px;
+}