--- a/addon-sdk/source/python-lib/cuddlefish/prefs.py
+++ b/addon-sdk/source/python-lib/cuddlefish/prefs.py
@@ -32,19 +32,16 @@ DEFAULT_COMMON_PREFS = {
     # Disable intalling any distribution add-ons
     'extensions.installDistroAddons' : False,
     # Allow installing extensions dropped into the profile folder
     'extensions.autoDisableScopes' : 10,
 
     # shut up some warnings on `about:` page
     'app.releaseNotesURL': 'http://localhost/app-dummy/',
     'app.vendorURL': 'http://localhost/app-dummy/',
-
-    # Don't prompt about e10s
-    'browser.displayedE10SPrompt.1': 5
 }
 
 DEFAULT_NO_CONNECTIONS_PREFS = {
     'toolkit.telemetry.enabled': False,
     'toolkit.telemetry.server': 'https://localhost/telemetry-dummy/',
     'app.update.auto' : False,
     'app.update.url': 'http://localhost/app-dummy/update',
     # Make sure GMPInstallManager won't hit the network.

--- a/addon-sdk/source/test/preferences/e10s-off.json
+++ b/addon-sdk/source/test/preferences/e10s-off.json
@@ -1,6 +1,5 @@
 {
-  "browser.displayedE10SPrompt.1": 5,
   "browser.tabs.remote.autostart": false,
   "browser.tabs.remote.autostart.1": false,
   "browser.tabs.remote.autostart.2": false
 }

--- a/browser/base/content/popup-notifications.inc
+++ b/browser/base/content/popup-notifications.inc
@@ -71,22 +71,16 @@
         <textbox id="login-fill-username" readonly="true"/>
         <textbox id="login-fill-password" type="password" disabled="true"/>
         <hbox>
           <button id="login-fill-use" label="Use in form"/>
         </hbox>
       </vbox>
     </stack>
 
-#ifdef E10S_TESTING_ONLY
-    <popupnotification id="enable-e10s-notification" hidden="true">
-      <popupnotificationcontent orient="vertical"/>
-    </popupnotification>
-#endif
-
     <popupnotification id="addon-progress-notification" hidden="true">
       <popupnotificationcontent orient="vertical">
         <progressmeter id="addon-progress-notification-progressmeter"/>
         <label id="addon-progress-notification-progresstext" crop="end"/>
       </popupnotificationcontent>
       <button id="addon-progress-cancel"
               oncommand="this.parentNode.cancel();"/>
       <button id="addon-progress-accept" disabled="true"/>

--- a/browser/components/nsBrowserGlue.js
+++ b/browser/components/nsBrowserGlue.js
@@ -112,21 +112,16 @@ XPCOMUtils.defineLazyModuleGetter(this, 
                                   "resource://gre/modules/LoginHelper.jsm");
 
 XPCOMUtils.defineLazyModuleGetter(this, "SimpleServiceDiscovery",
                                   "resource://gre/modules/SimpleServiceDiscovery.jsm");
 
 XPCOMUtils.defineLazyModuleGetter(this, "ContentSearch",
                                   "resource:///modules/ContentSearch.jsm");
 
-if (AppConstants.E10S_TESTING_ONLY) {
-  XPCOMUtils.defineLazyModuleGetter(this, "UpdateUtils",
-                                    "resource://gre/modules/UpdateUtils.jsm");
-}
-
 XPCOMUtils.defineLazyModuleGetter(this, "TabCrashHandler",
                                   "resource:///modules/ContentCrashHandlers.jsm");
 if (AppConstants.MOZ_CRASHREPORTER) {
   XPCOMUtils.defineLazyModuleGetter(this, "PluginCrashReporter",
                                     "resource:///modules/ContentCrashHandlers.jsm");
 }
 
 XPCOMUtils.defineLazyGetter(this, "gBrandBundle", function() {
@@ -2991,164 +2986,16 @@ var DefaultBrowserCheck = {
       let popup = doc.getElementById(this.OPTIONPOPUP);
       popup.removeEventListener("command", this);
       popup.remove();
       delete this._notification;
     }
   },
 };
 
-var E10SUINotification = {
-  CURRENT_PROMPT_PREF: "browser.displayedE10SPrompt.1",
-  PREVIOUS_PROMPT_PREF: "browser.displayedE10SPrompt",
-
-  get forcedOn() {
-    try {
-      return Services.prefs.getBoolPref("browser.tabs.remote.force-enable");
-    } catch (e) {}
-    return false;
-  },
-
-  get a11yRecentlyRan() {
-    try {
-      if (Services.prefs.getBoolPref("accessibility.loadedInLastSession")) {
-        return true;
-      }
-    } catch (e) {}
-    try {
-      Services.prefs.getBoolPref("accessibility.lastLoadDate");
-      return true;
-    } catch (e) {}
-    return false;
-  },
-
-  checkStatus: function() {
-    let updateChannel = UpdateUtils.UpdateChannel;
-    let channelAuthorized = updateChannel == "nightly" || updateChannel == "aurora";
-    if (!channelAuthorized) {
-      return;
-    }
-
-    if (!Services.appinfo.browserTabsRemoteAutostart) {
-      let displayFeedbackRequest = false;
-      try {
-        displayFeedbackRequest = Services.prefs.getBoolPref("browser.requestE10sFeedback");
-      } catch (e) {}
-
-      if (displayFeedbackRequest) {
-        let win = RecentWindow.getMostRecentBrowserWindow();
-        if (!win) {
-          return;
-        }
-
-        Services.prefs.clearUserPref("browser.requestE10sFeedback");
-
-        let url = Services.urlFormatter.formatURLPref("app.feedback.baseURL");
-        url += "?utm_source=tab&utm_campaign=e10sfeedback";
-
-        win.openUILinkIn(url, "tab");
-        return;
-      }
-
-      // If accessibility recently ran, don't prompt about trying out e10s
-      if (this.a11yRecentlyRan) {
-        return;
-      }
-
-      let e10sPromptShownCount = 0;
-      try {
-        e10sPromptShownCount = Services.prefs.getIntPref(this.CURRENT_PROMPT_PREF);
-      } catch(e) {}
-
-      let isHardwareAccelerated = true;
-      // Linux and Windows are currently ok, mac not so much.
-      if (AppConstants.platform == "macosx") {
-        try {
-          let win = RecentWindow.getMostRecentBrowserWindow();
-          let winutils = win.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindowUtils);
-          isHardwareAccelerated = winutils.layerManagerType != "Basic";
-        } catch (e) {}
-      }
-
-      if (!Services.appinfo.inSafeMode &&
-          !Services.appinfo.accessibilityEnabled &&
-          isHardwareAccelerated &&
-          e10sPromptShownCount < 5) {
-        Services.tm.mainThread.dispatch(() => {
-          try {
-            this._showE10SPrompt();
-            Services.prefs.setIntPref(this.CURRENT_PROMPT_PREF, e10sPromptShownCount + 1);
-            Services.prefs.clearUserPref(this.PREVIOUS_PROMPT_PREF);
-          } catch (ex) {
-            Cu.reportError("Failed to show e10s prompt: " + ex);
-          }
-        }, Ci.nsIThread.DISPATCH_NORMAL);
-      }
-    }
-  },
-
-  QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver, Ci.nsISupportsWeakReference]),
-
-  _showE10SPrompt: function BG__showE10SPrompt() {
-    let win = RecentWindow.getMostRecentBrowserWindow();
-    if (!win)
-      return;
-
-    let browser = win.gBrowser.selectedBrowser;
-
-    let promptMessage = win.gNavigatorBundle.getFormattedString(
-                          "e10s.offerPopup.mainMessage",
-                          [gBrandBundle.GetStringFromName("brandShortName")]
-                        );
-    let mainAction = {
-      label: win.gNavigatorBundle.getString("e10s.offerPopup.enableAndRestart.label"),
-      accessKey: win.gNavigatorBundle.getString("e10s.offerPopup.enableAndRestart.accesskey"),
-      callback: function () {
-        Services.prefs.setBoolPref("browser.tabs.remote.autostart", true);
-        Services.prefs.setBoolPref("browser.enabledE10SFromPrompt", true);
-        // Restart the app
-        let cancelQuit = Cc["@mozilla.org/supports-PRBool;1"].createInstance(Ci.nsISupportsPRBool);
-        Services.obs.notifyObservers(cancelQuit, "quit-application-requested", "restart");
-        if (cancelQuit.data)
-          return; // somebody canceled our quit request
-        Services.startup.quit(Services.startup.eAttemptQuit | Services.startup.eRestart);
-      }
-    };
-    let secondaryActions = [
-      {
-        label: win.gNavigatorBundle.getString("e10s.offerPopup.noThanks.label"),
-        accessKey: win.gNavigatorBundle.getString("e10s.offerPopup.noThanks.accesskey"),
-        callback: function () {
-          Services.prefs.setIntPref(E10SUINotification.CURRENT_PROMPT_PREF, 5);
-        }
-      }
-    ];
-    let options = {
-      popupIconURL: "chrome://browser/skin/e10s-64@2x.png",
-      learnMoreURL: "https://wiki.mozilla.org/Electrolysis",
-      persistWhileVisible: true
-    };
-
-    win.PopupNotifications.show(browser, "enable-e10s", promptMessage, null, mainAction, secondaryActions, options);
-
-    let highlights = [
-      win.gNavigatorBundle.getString("e10s.offerPopup.highlight1"),
-      win.gNavigatorBundle.getString("e10s.offerPopup.highlight2")
-    ];
-
-    let doorhangerExtraContent = win.document.getElementById("enable-e10s-notification")
-                                             .querySelector("popupnotificationcontent");
-    for (let highlight of highlights) {
-      let highlightLabel = win.document.createElement("label");
-      highlightLabel.setAttribute("value", highlight);
-      doorhangerExtraContent.appendChild(highlightLabel);
-    }
-  }
-};
-
 var E10SAccessibilityCheck = {
   init: function() {
     Services.obs.addObserver(this, "a11y-init-or-shutdown", true);
     Services.obs.addObserver(this, "quit-application-granted", true);
   },
 
   QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver, Ci.nsISupportsWeakReference]),
 

--- a/browser/components/preferences/in-content/main.js
+++ b/browser/components/preferences/in-content/main.js
@@ -156,22 +156,16 @@ var gMainPane = {
                                    "restart");
       shouldProceed = !cancelQuit.data;
 
       if (shouldProceed) {
         for (let prefToChange of prefsToChange) {
           prefToChange.value = e10sCheckbox.checked;
         }
 
-        let tmp = {};
-        Components.utils.import("resource://gre/modules/UpdateUtils.jsm", tmp);
-        if (!e10sCheckbox.checked && tmp.UpdateUtils.UpdateChannel != "default") {
-          Services.prefs.setBoolPref("browser.requestE10sFeedback", true);
-          Services.prompt.alert(window, brandName, bundle.getString("e10sFeedbackAfterRestart"));
-        }
         Services.startup.quit(Ci.nsIAppStartup.eAttemptQuit |  Ci.nsIAppStartup.eRestart);
       }
     }
 
     // Revert the checkbox in case we didn't quit
     e10sCheckbox.checked = e10sPref.value || e10sTempPref.value;
   },
 #endif

--- a/browser/locales/en-US/chrome/browser/browser.properties
+++ b/browser/locales/en-US/chrome/browser/browser.properties
@@ -688,37 +688,23 @@ readingList.promo.firstUse.readerView.bo
 # https://www.mozilla.org/firefox/android/.
 # %2$S will be replaced with a link, the text of which is
 # appMenuRemoteTabs.mobilePromo.ios
 # and the link will be to https://www.mozilla.org/firefox/ios/.
 appMenuRemoteTabs.mobilePromo.text2 = Download %1$S or %2$S and connect them to your Firefox Account.
 appMenuRemoteTabs.mobilePromo.android = Firefox for Android
 appMenuRemoteTabs.mobilePromo.ios = Firefox for iOS
 
-# LOCALIZATION NOTE (e10s.offerPopup.mainMessage
-#                    e10s.offerPopup.highlight1
-#                    e10s.offerPopup.highlight2
-#                    e10s.offerPopup.enableAndRestart.label
-#                    e10s.offerPopup.enableAndRestart.accesskey
-#                    e10s.offerPopup.noThanks.label
-#                    e10s.offerPopup.noThanks.accesskey
-#                    e10s.accessibilityNotice.mainMessage
-#                    e10s.accessibilityNotice.enableAndRestart.label
-#                    e10s.accessibilityNotice.enableAndRestart.accesskey
+# LOCALIZATION NOTE (e10s.accessibilityNotice.mainMessage,
+#                    e10s.accessibilityNotice.enableAndRestart.label,
+#                    e10s.accessibilityNotice.enableAndRestart.accesskey):
 # These strings are related to the messages we display to offer e10s (Multi-process) to users
 # on the pre-release channels. They won't be used in release but they will likely be used in
 # beta starting from version 41, so it's still useful to have these strings properly localized.
 # %S is brandShortName
-e10s.offerPopup.mainMessage = Multi-process is coming soon to %S. You can start using it now to get early access to some of the benefits:
-e10s.offerPopup.highlight1 = Improved responsiveness
-e10s.offerPopup.highlight2 = Fewer crashes
-e10s.offerPopup.enableAndRestart.label = Enable and Restart
-e10s.offerPopup.enableAndRestart.accesskey = E
-e10s.offerPopup.noThanks.label = No, thanks
-e10s.offerPopup.noThanks.accesskey = N
 e10s.accessibilityNotice.mainMessage2 = Accessibility support is partially disabled due to compatibility issues with new %S features.
 e10s.accessibilityNotice.acceptButton.label = OK
 e10s.accessibilityNotice.acceptButton.accesskey = O
 e10s.accessibilityNotice.enableAndRestart.label = Enable (Requires Restart)
 e10s.accessibilityNotice.enableAndRestart.accesskey = E
 
 # LOCALIZATION NOTE (usercontext.personal.label,
 #                    usercontext.work.label,

--- a/browser/locales/en-US/chrome/browser/preferences/preferences.properties
+++ b/browser/locales/en-US/chrome/browser/preferences/preferences.properties
@@ -170,13 +170,8 @@ syncUnlinkConfirm.label=Unlink
 featureEnableRequiresRestart=%S must restart to enable this feature.
 featureDisableRequiresRestart=%S must restart to disable this feature.
 shouldRestartTitle=Restart %S
 okToRestartButton=Restart %S now
 revertNoRestartButton=Revert
 
 restartNow=Restart Now
 restartLater=Restart Later
-
-#### e10S
-# LOCALIZATION NOTE (e10sFeedbackAfterRestart): This message appears when the user
-# unchecks "Enable multi-process" on the "General" preferences tab.
-e10sFeedbackAfterRestart=After restart, a tab will open to input.mozilla.org where you can provide us feedback about your e10s experience.

--- a/testing/marionette/client/marionette_driver/geckoinstance.py
+++ b/testing/marionette/client/marionette_driver/geckoinstance.py
@@ -10,21 +10,16 @@ import time
 from copy import deepcopy
 
 from mozprofile import Profile
 from mozrunner import Runner
 
 
 class GeckoInstance(object):
     required_prefs = {
-        "browser.displayedE10SPrompt.1": 5,
-        "browser.displayedE10SPrompt.2": 5,
-        "browser.displayedE10SPrompt.3": 5,
-        "browser.displayedE10SPrompt.4": 5,
-        "browser.displayedE10SPrompt": 5,
         "browser.sessionstore.resume_from_crash": False,
         "browser.shell.checkDefaultBrowser": False,
         "browser.startup.page": 0,
         "browser.tabs.remote.autostart.1": False,
         "browser.tabs.remote.autostart.2": False,
         "browser.tabs.remote.autostart": False,
         "browser.urlbar.userMadeSearchSuggestionsChoice": True,
         "browser.warnOnQuit": False,

--- a/testing/profiles/prefs_general.js
+++ b/testing/profiles/prefs_general.js
@@ -305,18 +305,16 @@ user_pref("browser.selfsupport.url", "ht
 user_pref("media.eme.enabled", true);
 
 user_pref("media.autoplay.enabled", true);
 
 #if defined(XP_WIN)
 user_pref("media.decoder.heuristic.dormant.timeout", 0);
 #endif
 
-// Don't prompt about e10s
-user_pref("browser.displayedE10SPrompt.1", 5);
 // Don't use auto-enabled e10s
 user_pref("browser.tabs.remote.autostart.1", false);
 user_pref("browser.tabs.remote.autostart.2", false);
 // Don't forceably kill content processes after a timeout
 user_pref("dom.ipc.tabs.shutdownTimeoutSecs", 0);
 
 // Don't block add-ons for e10s
 user_pref("extensions.e10sBlocksEnabling", false);

--- a/testing/talos/talos/config.py
+++ b/testing/talos/talos/config.py
@@ -165,22 +165,16 @@ DEFAULTS = dict(
         'browser.webapps.checkForUpdates': 0,
         'browser.search.geoSpecificDefaults': False,
         'browser.snippets.enabled': False,
         'browser.snippets.syncPromo.enabled': False,
         'toolkit.telemetry.server': 'https://127.0.0.1/telemetry-dummy/',
         'experiments.manifest.uri':
             'https://127.0.0.1/experiments-dummy/manifest',
         'network.http.speculative-parallel-limit': 0,
-        'browser.displayedE10SPrompt': 9999,
-        'browser.displayedE10SPrompt.1': 9999,
-        'browser.displayedE10SPrompt.2': 9999,
-        'browser.displayedE10SPrompt.3': 9999,
-        'browser.displayedE10SPrompt.4': 9999,
-        'browser.displayedE10SPrompt.5': 9999,
         'app.update.badge': False,
         'lightweightThemes.selectedThemeID': "",
         'devtools.webide.widget.enabled': False,
         'devtools.webide.widget.inNavbarByDefault': False,
         'devtools.chrome.enabled': False,
         'devtools.debugger.remote-enabled': False,
         'devtools.theme': "light",
         'devtools.timeline.enabled': False,

--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -8812,21 +8812,16 @@
     "bug_numbers": [1241294],
     "description": "Why e10s is enabled or disabled (0=ENABLED_BY_USER, 1=ENABLED_BY_DEFAULT, 2=DISABLED_BY_USER, 3=DISABLED_IN_SAFE_MODE, 4=DISABLED_FOR_ACCESSIBILITY, 5=DISABLED_FOR_MAC_GFX, 6=DISABLED_FOR_BIDI, 7=DISABLED_FOR_ADDONS)"
   },
   "E10S_WINDOW": {
     "expires_in_version": "never",
     "kind": "boolean",
     "description": "Whether a browser window is set as an e10s window"
   },
-  "E10S_STILL_ACCEPTED_FROM_PROMPT": {
-    "expires_in_version": "never",
-    "kind": "boolean",
-    "description": "Whether a user who accepted e10s from the prompt is still using e10s"
-  },
   "E10S_BLOCKED_FROM_RUNNING": {
     "expires_in_version": "never",
     "kind": "boolean",
     "description": "Whether the e10s pref was set but it was blocked from running due to blacklisted conditions"
   },
   "E10S_ADDONS_BLOCKER_RAN": {
     "alert_emails": ["firefox-dev@mozilla.org"],
     "expires_in_version": "49",

--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -4867,20 +4867,16 @@ mozilla::BrowserTabsRemoteAutostart()
       Preferences::GetBool(kForceDisableE10sPref, false)) {
     gBrowserTabsRemoteAutostart = false;
     status = kE10sForceDisabled;
   }
 
   gBrowserTabsRemoteStatus = status;
 
   mozilla::Telemetry::Accumulate(mozilla::Telemetry::E10S_STATUS, status);
-  if (Preferences::GetBool("browser.enabledE10SFromPrompt", false)) {
-    mozilla::Telemetry::Accumulate(mozilla::Telemetry::E10S_STILL_ACCEPTED_FROM_PROMPT,
-                                    gBrowserTabsRemoteAutostart);
-  }
   if (prefEnabled) {
     mozilla::Telemetry::Accumulate(mozilla::Telemetry::E10S_BLOCKED_FROM_RUNNING,
                                     !gBrowserTabsRemoteAutostart);
   }
   if (Preferences::HasUserValue("extensions.e10sBlockedByAddons")) {
     mozilla::Telemetry::Accumulate(mozilla::Telemetry::E10S_ADDONS_BLOCKER_RAN, true);
   }
   return gBrowserTabsRemoteAutostart;