diff --git a/accessible/jsat/Presentation.jsm b/accessible/jsat/Presentation.jsm
index 03b2f9205cc6..3c76426f621c 100644
--- a/accessible/jsat/Presentation.jsm
+++ b/accessible/jsat/Presentation.jsm
@@ -471,6 +471,169 @@ AndroidPresenter.prototype.noMove =
     };
   };
 
+/**
+ * A B2G presenter for Gaia.
+ */
+function B2GPresenter() {}
+
+B2GPresenter.prototype = Object.create(Presenter.prototype);
+
+B2GPresenter.prototype.type = "B2G";
+
+B2GPresenter.prototype.keyboardEchoSetting =
+  new PrefCache("accessibility.accessfu.keyboard_echo");
+B2GPresenter.prototype.NO_ECHO = 0;
+B2GPresenter.prototype.CHARACTER_ECHO = 1;
+B2GPresenter.prototype.WORD_ECHO = 2;
+B2GPresenter.prototype.CHARACTER_AND_WORD_ECHO = 3;
+
+/**
+ * A pattern used for haptic feedback.
+ * @type {Array}
+ */
+B2GPresenter.prototype.PIVOT_CHANGE_HAPTIC_PATTERN = [40];
+
+/**
+ * Pivot move reasons.
+ * @type {Array}
+ */
+B2GPresenter.prototype.pivotChangedReasons = ["none", "next", "prev", "first",
+                                              "last", "text", "point"];
+
+B2GPresenter.prototype.pivotChanged =
+  function B2GPresenter_pivotChanged(aContext, aReason, aIsUserInput) {
+    if (!aContext.accessible) {
+      return null;
+    }
+
+    return {
+      type: this.type,
+      details: {
+        eventType: "vc-change",
+        data: UtteranceGenerator.genForContext(aContext),
+        options: {
+          pattern: this.PIVOT_CHANGE_HAPTIC_PATTERN,
+          isKey: Utils.isActivatableOnFingerUp(aContext.accessible),
+          reason: this.pivotChangedReasons[aReason],
+          isUserInput: aIsUserInput,
+          hints: aContext.interactionHints
+        }
+      }
+    };
+  };
+
+B2GPresenter.prototype.nameChanged =
+  function B2GPresenter_nameChanged(aAccessible, aIsPolite = true) {
+    return {
+      type: this.type,
+      details: {
+        eventType: "name-change",
+        data: aAccessible.name,
+        options: {enqueue: aIsPolite}
+      }
+    };
+  };
+
+B2GPresenter.prototype.valueChanged =
+  function B2GPresenter_valueChanged(aAccessible, aIsPolite = true) {
+
+    // the editable value changes are handled in the text changed presenter
+    if (Utils.getState(aAccessible).contains(States.EDITABLE)) {
+      return null;
+    }
+
+    return {
+      type: this.type,
+      details: {
+        eventType: "value-change",
+        data: aAccessible.value,
+        options: {enqueue: aIsPolite}
+      }
+    };
+  };
+
+B2GPresenter.prototype.textChanged = function B2GPresenter_textChanged(
+  aAccessible, aIsInserted, aStart, aLength, aText, aModifiedText) {
+    let echoSetting = this.keyboardEchoSetting.value;
+    let text = "";
+
+    if (echoSetting == this.CHARACTER_ECHO ||
+        echoSetting == this.CHARACTER_AND_WORD_ECHO) {
+      text = aModifiedText;
+    }
+
+    // add word if word boundary is added
+    if ((echoSetting == this.WORD_ECHO ||
+        echoSetting == this.CHARACTER_AND_WORD_ECHO) &&
+        aIsInserted && aLength === 1) {
+      let accText = aAccessible.QueryInterface(Ci.nsIAccessibleText);
+      let startBefore = {}, endBefore = {};
+      let startAfter = {}, endAfter = {};
+      accText.getTextBeforeOffset(aStart,
+        Ci.nsIAccessibleText.BOUNDARY_WORD_END, startBefore, endBefore);
+      let maybeWord = accText.getTextBeforeOffset(aStart + 1,
+        Ci.nsIAccessibleText.BOUNDARY_WORD_END, startAfter, endAfter);
+      if (endBefore.value !== endAfter.value) {
+        text += maybeWord;
+      }
+    }
+
+    return {
+      type: this.type,
+      details: {
+        eventType: "text-change",
+        data: text
+      }
+    };
+
+  };
+
+B2GPresenter.prototype.actionInvoked =
+  function B2GPresenter_actionInvoked(aObject, aActionName) {
+    return {
+      type: this.type,
+      details: {
+        eventType: "action",
+        data: UtteranceGenerator.genForAction(aObject, aActionName)
+      }
+    };
+  };
+
+B2GPresenter.prototype.liveRegion = function B2GPresenter_liveRegion(aContext,
+  aIsPolite, aIsHide, aModifiedText) {
+    return {
+      type: this.type,
+      details: {
+        eventType: "liveregion-change",
+        data: UtteranceGenerator.genForLiveRegion(aContext, aIsHide,
+          aModifiedText),
+        options: {enqueue: aIsPolite}
+      }
+    };
+  };
+
+B2GPresenter.prototype.announce =
+  function B2GPresenter_announce(aAnnouncement) {
+    return {
+      type: this.type,
+      details: {
+        eventType: "announcement",
+        data: aAnnouncement
+      }
+    };
+  };
+
+B2GPresenter.prototype.noMove =
+  function B2GPresenter_noMove(aMoveMethod) {
+    return {
+      type: this.type,
+      details: {
+        eventType: "no-move",
+        data: aMoveMethod
+      }
+    };
+  };
+
 /**
  * A braille presenter
  */
@@ -513,7 +676,8 @@ var Presentation = { // jshint ignore:line
     delete this.presenters;
     let presenterMap = {
       "mobile/android": [VisualPresenter, AndroidPresenter],
-      "browser": [VisualPresenter, AndroidPresenter]
+      "b2g": [VisualPresenter, B2GPresenter],
+      "browser": [VisualPresenter, B2GPresenter, AndroidPresenter]
     };
     this.presenters = presenterMap[Utils.MozBuildApp].map(P => new P());
     return this.presenters;
diff --git a/accessible/jsat/Utils.jsm b/accessible/jsat/Utils.jsm
index dda853190aea..2fbcde34d3cc 100644
--- a/accessible/jsat/Utils.jsm
+++ b/accessible/jsat/Utils.jsm
@@ -26,8 +26,11 @@ var EXPORTED_SYMBOLS = ["Utils", "Logger", "PivotContext", "PrefCache"]; // jshi
 
 var Utils = { // jshint ignore:line
   _buildAppMap: {
+    "{3c2e2abc-06d4-11e1-ac3b-374f68613e61}": "b2g",
+    "{d1bfe7d9-c01e-4237-998b-7b5f960a4314}": "graphene",
     "{ec8030f7-c20a-464f-9b0e-13a3a9e97384}": "browser",
-    "{aa3c5121-dab2-40e2-81ca-7ea25febc110}": "mobile/android"
+    "{aa3c5121-dab2-40e2-81ca-7ea25febc110}": "mobile/android",
+    "{a23983c0-fd0e-11dc-95ff-0800200c9a66}": "mobile/xul"
   },
 
   init: function Utils_init(aWindow) {
@@ -130,6 +133,8 @@ var Utils = { // jshint ignore:line
         return this.win.BrowserApp;
       case "browser":
         return this.win.gBrowser;
+      case "b2g":
+        return this.win.shell;
       default:
         return null;
     }
@@ -139,6 +144,9 @@ var Utils = { // jshint ignore:line
     if (!this.BrowserApp) {
       return null;
     }
+    if (this.MozBuildApp == "b2g") {
+      return this.BrowserApp.contentBrowser;
+    }
     return this.BrowserApp.selectedBrowser;
   },
 
@@ -167,6 +175,13 @@ var Utils = { // jshint ignore:line
     let document = this.CurrentContentDoc;
 
     if (document) {
+      if (document.location.host === "b2g") {
+        // The document is a b2g app chrome (ie. Mulet).
+        let contentBrowser = this.win.content.shell.contentBrowser;
+        messageManagers.add(this.getMessageManager(contentBrowser));
+        document = contentBrowser.contentDocument;
+      }
+
       let remoteframes = document.querySelectorAll("iframe");
 
       for (let i = 0; i < remoteframes.length; ++i) {
diff --git a/accessible/tests/mochitest/hittest/a11y.ini b/accessible/tests/mochitest/hittest/a11y.ini
index 17af9d768c3a..ca79008639fc 100644
--- a/accessible/tests/mochitest/hittest/a11y.ini
+++ b/accessible/tests/mochitest/hittest/a11y.ini
@@ -5,7 +5,7 @@ support-files = zoom_tree.xul
 
 [test_browser.html]
 [test_canvas_hitregion.html]
-skip-if = (os == "android")
+skip-if = (os == "android" || appname == "b2g")
 [test_general.html]
 [test_menu.xul]
 [test_shadowroot.html]
diff --git a/accessible/tests/mochitest/jsat/jsatcommon.js b/accessible/tests/mochitest/jsat/jsatcommon.js
index 37c283cc8b5e..3f5cefdfd193 100644
--- a/accessible/tests/mochitest/jsat/jsatcommon.js
+++ b/accessible/tests/mochitest/jsat/jsatcommon.js
@@ -534,8 +534,11 @@ ExpectedMessage.prototype.ignore = function(aMessage) {
   return aMessage.name !== this.name;
 };
 
-function ExpectedPresent(aAndroid, aOptions) {
+function ExpectedPresent(aB2g, aAndroid, aOptions) {
   ExpectedMessage.call(this, "AccessFu:Present", aOptions);
+  if (aB2g) {
+    this.json.b2g = aB2g;
+  }
 
   if (aAndroid) {
     this.json.android = aAndroid;
@@ -547,7 +550,7 @@ ExpectedPresent.prototype = Object.create(ExpectedMessage.prototype);
 ExpectedPresent.prototype.is = function(aReceived, aInfo) {
   var received = this.extract_presenters(aReceived);
 
-  for (var presenter of ["android"]) {
+  for (var presenter of ["b2g", "android"]) {
     if (!this.options["no_" + presenter]) {
       var todo = this.options.todo || this.options[presenter + "_todo"];
       SimpleTest[todo ? "todo" : "ok"].apply(
@@ -602,6 +605,8 @@ function ExpectedCursorTextChange(aSpeech, aStartOffset, aEndOffset, aOptions) {
     toIndex: aEndOffset
   }], aOptions);
 
+  // bug 980509
+  this.options.b2g_todo = true;
 }
 
 ExpectedCursorTextChange.prototype =
diff --git a/accessible/tests/mochitest/jsat/test_content_integration.html b/accessible/tests/mochitest/jsat/test_content_integration.html
index 9d3d484a08ad..9786571bf759 100644
--- a/accessible/tests/mochitest/jsat/test_content_integration.html
+++ b/accessible/tests/mochitest/jsat/test_content_integration.html
@@ -110,7 +110,7 @@
           // Move from an inner frame to the last element in the parent doc
           [ContentMessages.simpleMoveLast,
             new ExpectedCursorChange(
-              ["slider", "0", {"string": "slider"}])],
+              ["slider", "0", {"string": "slider"}], { b2g_todo: true })],
 
           [ContentMessages.clearCursor, "AccessFu:CursorCleared"],
 
@@ -153,7 +153,7 @@
              {"string": "checkbutton"}, {"string": "listStart"},
              {"string": "list"}, {"string": "listItemsCount", "count": 1}])],
           [ContentMessages.simpleMoveFirst,
-            new ExpectedCursorChange(["Phone status bar"])],
+            new ExpectedCursorChange(["Phone status bar"], { b2g_todo: true })],
 
           // Reset cursors
           [ContentMessages.clearCursor, "AccessFu:CursorCleared"],
diff --git a/browser/components/BrowserComponents.manifest b/browser/components/BrowserComponents.manifest
index c43fcf8af052..dbfc3d2ec491 100644
--- a/browser/components/BrowserComponents.manifest
+++ b/browser/components/BrowserComponents.manifest
@@ -29,12 +29,15 @@ category command-line-validator b-browser @mozilla.org/browser/clh;1 application
 # to the specific list of apps that use it so it doesn't get loaded in xpcshell.
 # Thus we restrict it to these apps:
 #
+#   b2g:            {3c2e2abc-06d4-11e1-ac3b-374f68613e61}
 #   browser:        {ec8030f7-c20a-464f-9b0e-13a3a9e97384}
 #   mobile/android: {aa3c5121-dab2-40e2-81ca-7ea25febc110}
+#   mobile/xul:     {a23983c0-fd0e-11dc-95ff-0800200c9a66}
+#   graphene:       {d1bfe7d9-c01e-4237-998b-7b5f960a4314}
 
 component {eab9012e-5f74-4cbc-b2b5-a590235513cc} nsBrowserGlue.js
 contract @mozilla.org/browser/browserglue;1 {eab9012e-5f74-4cbc-b2b5-a590235513cc}
-category app-startup nsBrowserGlue service,@mozilla.org/browser/browserglue;1 application={ec8030f7-c20a-464f-9b0e-13a3a9e97384} application={aa3c5121-dab2-40e2-81ca-7ea25febc110}
+category app-startup nsBrowserGlue service,@mozilla.org/browser/browserglue;1 application={3c2e2abc-06d4-11e1-ac3b-374f68613e61} application={ec8030f7-c20a-464f-9b0e-13a3a9e97384} application={aa3c5121-dab2-40e2-81ca-7ea25febc110} application={a23983c0-fd0e-11dc-95ff-0800200c9a66} application={d1bfe7d9-c01e-4237-998b-7b5f960a4314}
 component {d8903bf6-68d5-4e97-bcd1-e4d3012f721a} nsBrowserGlue.js
 #ifndef MOZ_MULET
 contract @mozilla.org/content-permission/prompt;1 {d8903bf6-68d5-4e97-bcd1-e4d3012f721a}
diff --git a/browser/components/feeds/BrowserFeeds.manifest b/browser/components/feeds/BrowserFeeds.manifest
index c0d63cba37c9..9088eb0373f2 100644
--- a/browser/components/feeds/BrowserFeeds.manifest
+++ b/browser/components/feeds/BrowserFeeds.manifest
@@ -2,8 +2,11 @@
 # to the specific list of apps that use it so it doesn't get loaded in xpcshell.
 # Thus we restrict it to these apps:
 #
+#   b2g:            {3c2e2abc-06d4-11e1-ac3b-374f68613e61}
 #   browser:        {ec8030f7-c20a-464f-9b0e-13a3a9e97384}
 #   mobile/android: {aa3c5121-dab2-40e2-81ca-7ea25febc110}
+#   mobile/xul:     {a23983c0-fd0e-11dc-95ff-0800200c9a66}
+#   graphene:       {d1bfe7d9-c01e-4237-998b-7b5f960a4314}
 
 component {229fa115-9412-4d32-baf3-2fc407f76fb1} FeedConverter.js
 contract @mozilla.org/streamconv;1?from=application/vnd.mozilla.maybe.feed&to=*/* {229fa115-9412-4d32-baf3-2fc407f76fb1}
@@ -15,4 +18,4 @@ component {49bb6593-3aff-4eb3-a068-2712c28bd58e} FeedWriter.js
 contract @mozilla.org/browser/feeds/result-writer;1 {49bb6593-3aff-4eb3-a068-2712c28bd58e}
 component {792a7e82-06a0-437c-af63-b2d12e808acc} WebContentConverter.js
 contract @mozilla.org/embeddor.implemented/web-content-handler-registrar;1 {792a7e82-06a0-437c-af63-b2d12e808acc}
-category app-startup WebContentConverter service,@mozilla.org/embeddor.implemented/web-content-handler-registrar;1 application={ec8030f7-c20a-464f-9b0e-13a3a9e97384} application={aa3c5121-dab2-40e2-81ca-7ea25febc110}
+category app-startup WebContentConverter service,@mozilla.org/embeddor.implemented/web-content-handler-registrar;1 application={3c2e2abc-06d4-11e1-ac3b-374f68613e61} application={ec8030f7-c20a-464f-9b0e-13a3a9e97384} application={aa3c5121-dab2-40e2-81ca-7ea25febc110} application={a23983c0-fd0e-11dc-95ff-0800200c9a66} application={d1bfe7d9-c01e-4237-998b-7b5f960a4314}
diff --git a/browser/components/sessionstore/nsSessionStore.manifest b/browser/components/sessionstore/nsSessionStore.manifest
index 1d98adc3b9f2..9b5819c6a37c 100644
--- a/browser/components/sessionstore/nsSessionStore.manifest
+++ b/browser/components/sessionstore/nsSessionStore.manifest
@@ -2,11 +2,14 @@
 # to the specific list of apps that use it so it doesn't get loaded in xpcshell.
 # Thus we restrict it to these apps:
 #
+#   b2g:            {3c2e2abc-06d4-11e1-ac3b-374f68613e61}
 #   browser:        {ec8030f7-c20a-464f-9b0e-13a3a9e97384}
 #   mobile/android: {aa3c5121-dab2-40e2-81ca-7ea25febc110}
+#   mobile/xul:     {a23983c0-fd0e-11dc-95ff-0800200c9a66}
+#   graphene:       {d1bfe7d9-c01e-4237-998b-7b5f960a4314}
 
 component {5280606b-2510-4fe0-97ef-9b5a22eafe6b} nsSessionStore.js
 contract @mozilla.org/browser/sessionstore;1 {5280606b-2510-4fe0-97ef-9b5a22eafe6b}
 component {ec7a6c20-e081-11da-8ad9-0800200c9a66} nsSessionStartup.js
 contract @mozilla.org/browser/sessionstartup;1 {ec7a6c20-e081-11da-8ad9-0800200c9a66}
-category app-startup nsSessionStartup service,@mozilla.org/browser/sessionstartup;1 application={ec8030f7-c20a-464f-9b0e-13a3a9e97384} application={aa3c5121-dab2-40e2-81ca-7ea25febc110}
+category app-startup nsSessionStartup service,@mozilla.org/browser/sessionstartup;1 application={3c2e2abc-06d4-11e1-ac3b-374f68613e61} application={ec8030f7-c20a-464f-9b0e-13a3a9e97384} application={aa3c5121-dab2-40e2-81ca-7ea25febc110} application={a23983c0-fd0e-11dc-95ff-0800200c9a66} application={d1bfe7d9-c01e-4237-998b-7b5f960a4314}
diff --git a/browser/experiments/docs/manifest.rst b/browser/experiments/docs/manifest.rst
index 213a7517ae61..ab8c13f82c22 100644
--- a/browser/experiments/docs/manifest.rst
+++ b/browser/experiments/docs/manifest.rst
@@ -101,7 +101,7 @@ appName
    Array of application names this experiment should run on.
 
    An application name comes from ``nsIXULAppInfo.name``. It is a value
-   like ``Firefox`` or ``Fennec``.
+   like ``Firefox``, ``Fennec``, or `B2G`.
 
    The client should compare its application name against the members of
    this array. If a match is found, the experiment is applicable.
diff --git a/build/docs/mozinfo.rst b/build/docs/mozinfo.rst
index 709ae87804d3..d44b814beee8 100644
--- a/build/docs/mozinfo.rst
+++ b/build/docs/mozinfo.rst
@@ -63,7 +63,7 @@ buildapp
    The path to the XUL application being built.
 
    For desktop Firefox, this is ``browser``. For Fennec, it's
-   ``mobile/android``.
+   ``mobile/android``. For B2G, it's ``b2g``.
 
 crashreporter
    Whether the crash reporter is enabled for this build.
@@ -114,7 +114,7 @@ nightly_build
 
 os
    The operating system the build is produced for. Values for tier-1
-   supported platforms are ``linux``, ``win``, ``mac``, and
+   supported platforms are ``linux``, ``win``, ``mac``, ``b2g``, and
    ``android``. For other platforms, the value is the lowercase version
    of the ``OS_TARGET`` variable from ``config.status``.
 
diff --git a/build/unix/mozconfig.linux b/build/unix/mozconfig.linux
index 0d52daee5b85..b5da799acd20 100644
--- a/build/unix/mozconfig.linux
+++ b/build/unix/mozconfig.linux
@@ -7,12 +7,21 @@ fi
 
 TOOLTOOL_DIR=${TOOLTOOL_DIR:-$topsrcdir}
 
-# We deal with valgrind builds here
-CC="$TOOLTOOL_DIR/gcc/bin/gcc"
-CXX="$TOOLTOOL_DIR/gcc/bin/g++"
+# some b2g desktop builds still happen on i686 machines, and the tooltool
+# toolchain is x86_64 only.
+# We also deal with valgrind builds here, they don't use tooltool manifests at
+# all yet.
+if [ -z "$no_tooltool" ]
+then
+  CC="$TOOLTOOL_DIR/gcc/bin/gcc"
+  CXX="$TOOLTOOL_DIR/gcc/bin/g++"
 
-# We want to make sure we use binutils and other binaries in the tooltool
-# package.
-mk_add_options "export PATH=$TOOLTOOL_DIR/gcc/bin:$PATH"
+  # We want to make sure we use binutils and other binaries in the tooltool
+  # package.
+  mk_add_options "export PATH=$TOOLTOOL_DIR/gcc/bin:$PATH"
+else
+  CC="/tools/gcc-4.7.3-0moz1/bin/gcc"
+  CXX="/tools/gcc-4.7.3-0moz1/bin/g++"
+fi
 
 . "$topsrcdir/build/unix/mozconfig.stdcxx"
diff --git a/devtools/docs/backend/actor-registration.md b/devtools/docs/backend/actor-registration.md
index 0e1090285e74..6355dfb288aa 100644
--- a/devtools/docs/backend/actor-registration.md
+++ b/devtools/docs/backend/actor-registration.md
@@ -4,9 +4,9 @@
 
 Tab actors are the most common types of actors. That's the type of actors you will most probably be adding.
 
-Tab actors target a document, this could be a tab in Firefox or a remote document in Firefox for Android/Safari/Chrome for Android (via Valence).
+Tab actors target a document, this could be a tab in Firefox, an app on B2G or a remote document in Firefox for Android/Safari/Chrome for Android (via Valence).
 
-Global actors however are for the rest, for things not related to any particular document but instead for things global to the whole Firefox/Chrome/Safari intance the toolbox is connected to (e.g. the preference actor).
+Global actors however are for the rest, for things not related to any particular document but instead for things global to the whole Firefox/B2G/Chrome/Safari intance the toolbox is connected to (e.g. the preference actor).
 
 ## The DebuggerServer.registerModule function
 
@@ -38,4 +38,4 @@ If you are adding a new actor from an add-on, you should call `DebuggerServer.re
 
 The `DebuggerServer` loads and creates all of the actors lazily to keep the initial memory usage down (which is extremely important on lower end devices).
 
-It becomes especially important when debugging pages with e10s when there are more than one process, because that's when we need to spawn a `DebuggerServer` per process (it may not be immediately obvious that the server in the main process is mostly only here for piping messages to the actors in the child process).
+It becomes especially important when debugging apps on b2g or pages with e10s when there are more than one process, because that's when we need to spawn a `DebuggerServer` per process (it may not be immediately obvious that the server in the main process is mostly only here for piping messages to the actors in the child process).
diff --git a/devtools/shared/system.js b/devtools/shared/system.js
index 4c289658945d..85bf2168d186 100644
--- a/devtools/shared/system.js
+++ b/devtools/shared/system.js
@@ -39,7 +39,9 @@ const APP_MAP = {
   "{3550f703-e582-4d05-9a08-453d09bdfdc6}": "thunderbird",
   "{92650c4d-4b8e-4d2a-b7eb-24ecf4f6b63a}": "seamonkey",
   "{718e30fb-e89b-41dd-9da7-e25a45638b28}": "sunbird",
-  "{aa3c5121-dab2-40e2-81ca-7ea25febc110}": "mobile/android"
+  "{3c2e2abc-06d4-11e1-ac3b-374f68613e61}": "b2g",
+  "{aa3c5121-dab2-40e2-81ca-7ea25febc110}": "mobile/android",
+  "{a23983c0-fd0e-11dc-95ff-0800200c9a66}": "mobile/xul"
 };
 
 var CACHED_INFO = null;
@@ -66,8 +68,22 @@ async function getSystemInfo() {
   let hardware = "unknown";
   let version = "unknown";
 
-  os = appInfo.OS;
-  version = appInfo.version;
+  // B2G specific
+  if (apptype === "b2g") {
+    os = "B2G";
+    // `getSetting` does not work in child processes on b2g.
+    // TODO bug 1205797, make this work in child processes.
+    try {
+      hardware = await exports.getSetting("deviceinfo.hardware");
+      version = await exports.getSetting("deviceinfo.os");
+    } catch (e) {
+      // Ignore.
+    }
+  } else {
+    // Not B2G
+    os = appInfo.OS;
+    version = appInfo.version;
+  }
 
   let bundle = Services.strings.createBundle("chrome://branding/locale/brand.properties");
   if (bundle) {
@@ -109,6 +125,7 @@ async function getSystemInfo() {
     // The application's version, for example "0.8.0+" or "3.7a1pre".
     // Typically, the version of Firefox, for example.
     // It is different than the version of Gecko or the XULRunner platform.
+    // On B2G, this is the Gaia version.
     version,
 
     // The application's build ID/date, for example "2004051604".
@@ -139,6 +156,7 @@ async function getSystemInfo() {
 
     // Name of the OS type. Typically the same as `uname -s`. Possible values:
     // https://developer.mozilla.org/en/OS_TARGET
+    // Also may be "B2G".
     os,
     platform: os,
 
@@ -253,6 +271,7 @@ function getSetting(name) {
   if ("@mozilla.org/settingsService;1" in Cc) {
     let settingsService;
 
+    // settingsService fails in b2g child processes
     // TODO bug 1205797, make this work in child processes.
     try {
       settingsService = Cc["@mozilla.org/settingsService;1"]
diff --git a/dom/cache/test/mochitest/serviceworker_driver.js b/dom/cache/test/mochitest/serviceworker_driver.js
index b35d82fbffec..7b4374c2bc72 100644
--- a/dom/cache/test/mochitest/serviceworker_driver.js
+++ b/dom/cache/test/mochitest/serviceworker_driver.js
@@ -2,6 +2,13 @@
 // http://creativecommons.org/publicdomain/zero/1.0/
 
 function serviceWorkerTestExec(testFile) {
+  var isB2G = !navigator.userAgent.includes("Android") &&
+              /Mobile|Tablet/.test(navigator.userAgent);
+  if (isB2G) {
+    // TODO B2G doesn't support running service workers for now due to bug 1137683.
+    dump("Skipping running the test in SW until bug 1137683 gets fixed.\n");
+    return Promise.resolve();
+  }
   return new Promise(function(resolve, reject) {
     function setupSW(registration) {
       var worker = registration.waiting ||
diff --git a/dom/canvas/test/webgl-conf/generated-mochitest.ini b/dom/canvas/test/webgl-conf/generated-mochitest.ini
index 9addd844dda7..ff34fcb4feed 100644
--- a/dom/canvas/test/webgl-conf/generated-mochitest.ini
+++ b/dom/canvas/test/webgl-conf/generated-mochitest.ini
@@ -4,7 +4,7 @@
 
 [DEFAULT]
 subsuite = webgl
-skip-if = (os == 'linux') && (buildapp == 'mulet')
+skip-if = os == 'b2g' || ((os == 'linux') && (buildapp == 'mulet'))
 
 support-files = always-fail.html
                 checkout/00_test_list.txt
@@ -7537,7 +7537,7 @@ skip-if = (os == 'mac')
 [generated/test_conformance__context__constants-and-properties.html]
 [generated/test_conformance__context__context-attribute-preserve-drawing-buffer.html]
 [generated/test_conformance__context__context-attributes-alpha-depth-stencil-antialias.html]
-skip-if = (os == 'linux') || (os == 'android')
+skip-if = (os == 'b2g') || (os == 'linux') || (os == 'android')
 fail-if = (os == 'mac' && os_version == '10.6')
 [generated/test_conformance__context__context-creation-and-destruction.html]
 [generated/test_conformance__context__context-creation.html]
@@ -7931,10 +7931,12 @@ fail-if = (os == 'android')
 [generated/test_conformance__glsl__misc__uniform-location-length-limits.html]
 [generated/test_conformance__glsl__reserved___webgl_field.vert.html]
 [generated/test_conformance__glsl__reserved___webgl_function.vert.html]
+fail-if = (os == 'b2g')
 [generated/test_conformance__glsl__reserved___webgl_struct.vert.html]
 [generated/test_conformance__glsl__reserved___webgl_variable.vert.html]
 [generated/test_conformance__glsl__reserved__webgl_field.vert.html]
 [generated/test_conformance__glsl__reserved__webgl_function.vert.html]
+fail-if = (os == 'b2g')
 [generated/test_conformance__glsl__reserved__webgl_struct.vert.html]
 [generated/test_conformance__glsl__reserved__webgl_variable.vert.html]
 [generated/test_conformance__glsl__samplers__glsl-function-texture2d-bias.html]
@@ -7966,6 +7968,7 @@ skip-if = (os == 'android')
 [generated/test_conformance__misc__delayed-drawing.html]
 skip-if = (os == 'android' && android_version == '10')
 [generated/test_conformance__misc__error-reporting.html]
+fail-if = (os == 'b2g')
 [generated/test_conformance__misc__expando-loss.html]
 [generated/test_conformance__misc__functions-returning-strings.html]
 [generated/test_conformance__misc__instanceof-test.html]
@@ -7979,7 +7982,7 @@ fail-if = (os == 'android')
 [generated/test_conformance__misc__shader-precision-format.html]
 skip-if = (os == 'android')
 [generated/test_conformance__misc__type-conversion-test.html]
-skip-if = (os == 'android') || (os == 'linux')
+skip-if = (os == 'android') || (os == 'b2g') || (os == 'linux')
 fail-if = (os == 'linux')
 [generated/test_conformance__misc__uninitialized-test.html]
 skip-if = (os == 'android')
@@ -8205,6 +8208,7 @@ fail-if = (os == 'mac' && os_version == '10.6')
 [generated/test_conformance__ogles__GL__vec__vec_009_to_016.html]
 [generated/test_conformance__ogles__GL__vec__vec_017_to_018.html]
 [generated/test_conformance__programs__get-active-test.html]
+fail-if = (os == 'b2g')
 [generated/test_conformance__programs__gl-bind-attrib-location-long-names-test.html]
 [generated/test_conformance__programs__gl-bind-attrib-location-test.html]
 [generated/test_conformance__programs__gl-get-active-attribute.html]
diff --git a/dom/canvas/test/webgl-conf/mochitest-errata.ini b/dom/canvas/test/webgl-conf/mochitest-errata.ini
index 5ee6b2f9f1f4..feb259cae536 100644
--- a/dom/canvas/test/webgl-conf/mochitest-errata.ini
+++ b/dom/canvas/test/webgl-conf/mochitest-errata.ini
@@ -23,8 +23,9 @@
 
 [DEFAULT]
 subsuite = webgl
+# Skip B2G for now, until we get a handle on the longer tail of emulator bugs.
 # Bug 1136181 disabled on Mulet for intermittent failures
-skip-if = (os == 'linux') && (buildapp == 'mulet')
+skip-if = os == 'b2g' || ((os == 'linux') && (buildapp == 'mulet'))
 
 [generated/test_..__always-fail.html]
 fail-if = 1
@@ -75,8 +76,8 @@ skip-if = (os == 'win')
 
 [generated/test_conformance__context__context-attributes-alpha-depth-stencil-antialias.html]
 fail-if = (os == 'mac' && os_version == '10.6')
-# Asserts on linux debug. Crashes on Android.
-skip-if = (os == 'linux') || (os == 'android')
+# Asserts on 'B2G ICS Emulator Debug' and linux debug. Crashes on Android.
+skip-if = (os == 'b2g') || (os == 'linux') || (os == 'android')
 
 [generated/test_conformance__extensions__webgl-draw-buffers.html]
 # Crashes
@@ -111,8 +112,8 @@ fail-if = (os == 'linux')
 [generated/test_conformance__misc__type-conversion-test.html]
 fail-if = (os == 'linux')
 # Resets device on Android 2.3.
-# Crashes on desktop Linux, and Mulet Linux x64.
-skip-if = (os == 'android') || (os == 'linux')
+# Crashes on B2G ICS Emulator, desktop Linux, and Mulet Linux x64.
+skip-if = (os == 'android') || (os == 'b2g') || (os == 'linux')
 
 [generated/test_conformance__misc__object-deletion-behaviour.html]
 fail-if = (os == 'android')
@@ -337,10 +338,11 @@ fail-if = (os == 'mac') || (os == 'win')
 fail-if = (os == 'mac') || (os == 'win')
 ########################################################################
 # "tst-linux{32,64}-spot-NNN" Slaves:
-#   Android 2.3, Linux, and Mulet.
+#   Android 2.3, B2G Emu, Linux, and Mulet.
 # Android: os == 'android'. (Not enough info to separate out 2.3)
+# B2G Emu: os == 'b2g'.
 # Linux: os == 'linux'.
-# Mulet: buildapp == 'mulet'.
+# Mulet: os == 'b2g' && buildapp == 'mulet'.
 [generated/test_conformance__glsl__bugs__temp-expressions-should-not-crash.html]
 # Coincidentally enough, crashes on Linux and Android 4.0.
 skip-if = (os == 'android') || (os == 'linux')
@@ -355,6 +357,7 @@ fail-if = (os == 'android')
 [generated/test_conformance__reading__read-pixels-test.html]
 # Causes consistent *blues*: "DMError: Remote Device Error: unable to
 # connect to 127.0.0.1 after 5 attempts" on 'Android 2.3 Opt'.
+# Crashes near on B2G ICS Emulator.
 skip-if = (os == 'android') || (os == 'linux')
 [generated/test_conformance__textures__misc__texture-upload-size.html]
 # application crashed [@ mozilla::WebGLTexture::TexSubImage]
@@ -580,10 +583,16 @@ skip-if = (os == 'android')
 
 ########################################################################
 ########################################################################
+# B2G
 [generated/test_conformance__glsl__reserved___webgl_function.vert.html]
+fail-if = (os == 'b2g')
 [generated/test_conformance__glsl__reserved__webgl_function.vert.html]
+fail-if = (os == 'b2g')
 [generated/test_conformance__misc__error-reporting.html]
+fail-if = (os == 'b2g')
 [generated/test_conformance__programs__get-active-test.html]
+fail-if = (os == 'b2g')
+
 
 ########################################################################
 ########################################################################
diff --git a/mobile/android/modules/FormAssistant.jsm b/mobile/android/modules/FormAssistant.jsm
index 913b538c4845..c8d64b034c3b 100644
--- a/mobile/android/modules/FormAssistant.jsm
+++ b/mobile/android/modules/FormAssistant.jsm
@@ -235,6 +235,7 @@ var FormAssistant = {
   },
 
   /**
+   * (Copied from mobile/xul/chrome/content/forms.js)
    * This function is similar to getListSuggestions from
    * components/satchel/src/nsInputListAutoComplete.js but sadly this one is
    * used by the autocomplete.xml binding which is not in used in fennec
diff --git a/testing/mozbase/moztest/tests/test.py b/testing/mozbase/moztest/tests/test.py
index d63a4c906af9..ed2dd2d469fc 100644
--- a/testing/mozbase/moztest/tests/test.py
+++ b/testing/mozbase/moztest/tests/test.py
@@ -41,6 +41,7 @@ class Collection(unittest.TestCase):
         c1 = TestContext('host1')
         c2 = TestContext('host2')
         c3 = TestContext('host2')
+        c3.os = 'B2G'
         c4 = TestContext('host1')
 
         t1 = TestResult('t1', context=c1)
diff --git a/testing/mozbase/mozversion/tests/manifest.ini b/testing/mozbase/mozversion/tests/manifest.ini
index f42f5d384125..096fef68a953 100644
--- a/testing/mozbase/mozversion/tests/manifest.ini
+++ b/testing/mozbase/mozversion/tests/manifest.ini
@@ -2,4 +2,5 @@
 subsuite = mozbase, os == "linux"
 [test_binary.py]
 [test_sources.py]
+[test_b2g.py]
 [test_apk.py]
diff --git a/testing/mozbase/packages.txt b/testing/mozbase/packages.txt
index 77a1b551ef99..ba1f292ef38f 100644
--- a/testing/mozbase/packages.txt
+++ b/testing/mozbase/packages.txt
@@ -1,4 +1,5 @@
 manifestparser.pth:testing/mozbase/manifestparser
+mozb2g.pth:testing/mozbase/mozb2g
 mozcrash.pth:testing/mozbase/mozcrash
 mozdebug.pth:testing/mozbase/mozdebug
 mozdevice.pth:testing/mozbase/mozdevice
diff --git a/testing/mozharness/configs/multi_locale/standalone_mozilla-central.py b/testing/mozharness/configs/multi_locale/standalone_mozilla-central.py
index 50393cce4d55..e6688ad0339a 100644
--- a/testing/mozharness/configs/multi_locale/standalone_mozilla-central.py
+++ b/testing/mozharness/configs/multi_locale/standalone_mozilla-central.py
@@ -1,4 +1,3 @@
-
 import os
 # The name of the directory we'll pull our source into.
 BUILD_DIR = "mozilla-central"
@@ -11,6 +10,7 @@ REPO_PATH = "mozilla-central"
 L10N_REPO_PATH = "l10n-central"
 # Currently this is assumed to be a subdirectory of your build dir
 OBJDIR = "objdir-droid"
+# Set this to mobile/xul for XUL Fennec
 ANDROID_DIR = "mobile/android"
 # Absolute path to your mozconfig.
 # By default it looks at "./mozconfig"
diff --git a/toolkit/nss.configure b/toolkit/nss.configure
index f910b7ba3d07..734f4f029855 100644
--- a/toolkit/nss.configure
+++ b/toolkit/nss.configure
@@ -9,7 +9,7 @@
 # ==============================================================
 @depends(build_project, '--help')
 def dbm_default(build_project, _):
-    return build_project != 'mobile/android'
+    return build_project not in ('mobile/android', 'b2g', 'b2g/graphene')
 
 option('--enable-dbm', default=dbm_default, help='Enable building DBM')
 
diff --git a/toolkit/toolkit.mozbuild b/toolkit/toolkit.mozbuild
index 768bbcc5fbf4..afe7237d0b82 100644
--- a/toolkit/toolkit.mozbuild
+++ b/toolkit/toolkit.mozbuild
@@ -41,7 +41,8 @@ if CONFIG['MOZ_SANDBOX']:
     DIRS += ['/security/sandbox']
 
 DIRS += [
-    # Depends on NSS and NSPR
+    # Depends on NSS and NSPR, and must be built after sandbox or else B2G emulator
+    # builds fail.
     '/security/certverifier',
     # Depends on certverifier
     '/security/apps',
diff --git a/widget/NativeKeyToDOMKeyName.h b/widget/NativeKeyToDOMKeyName.h
index f35d25d17675..bfd5baa948b3 100644
--- a/widget/NativeKeyToDOMKeyName.h
+++ b/widget/NativeKeyToDOMKeyName.h
@@ -25,8 +25,12 @@
 #define KEY_MAP_COCOA(aCPPKeyName, aNativeKey)
 // GTK
 #define KEY_MAP_GTK(aCPPKeyName, aNativeKey)
-// Only for Android
+// Android and B2G
 #define KEY_MAP_ANDROID(aCPPKeyName, aNativeKey)
+// Only for Android
+#define KEY_MAP_ANDROID_EXCEPT_B2G(aCPPKeyName, aNativeKey)
+// Only for B2G
+#define KEY_MAP_B2G(aCPPKeyName, aNativeKey)
 
 #if defined(XP_WIN)
 #if defined(NS_NATIVE_KEY_TO_DOM_KEY_NAME_INDEX)
@@ -76,6 +80,9 @@
 #undef KEY_MAP_ANDROID
 #define KEY_MAP_ANDROID(aCPPKeyName, aNativeKey) \
   NS_NATIVE_KEY_TO_DOM_KEY_NAME_INDEX(aNativeKey, KEY_NAME_INDEX_##aCPPKeyName)
+#undef KEY_MAP_ANDROID_EXCEPT_B2G
+#define KEY_MAP_ANDROID_EXCEPT_B2G(aCPPKeyName, aNativeKey) \
+  NS_NATIVE_KEY_TO_DOM_KEY_NAME_INDEX(aNativeKey, KEY_NAME_INDEX_##aCPPKeyName)
 #endif
 
 /******************************************************************************
@@ -1049,7 +1056,7 @@ KEY_MAP_ANDROID (Call, AKEYCODE_CALL)
 KEY_MAP_ANDROID (Camera, AKEYCODE_CAMERA)
 
 // CameraFocus
-KEY_MAP_ANDROID(CameraFocus, AKEYCODE_FOCUS)
+KEY_MAP_ANDROID_EXCEPT_B2G(CameraFocus, AKEYCODE_FOCUS)
 
 // EndCall
 KEY_MAP_ANDROID (EndCall, AKEYCODE_ENDCALL)
@@ -1058,7 +1065,8 @@ KEY_MAP_ANDROID (EndCall, AKEYCODE_ENDCALL)
 KEY_MAP_ANDROID (GoBack, AKEYCODE_BACK)
 
 // GoHome
-KEY_MAP_ANDROID(GoHome,     AKEYCODE_HOME)
+KEY_MAP_ANDROID_EXCEPT_B2G(GoHome,     AKEYCODE_HOME)
+KEY_MAP_B2G               (HomeScreen, AKEYCODE_HOME)
 
 // HeadsetHook
 KEY_MAP_ANDROID (HeadsetHook, AKEYCODE_HEADSETHOOK)
@@ -1280,3 +1288,5 @@ KEY_MAP_ANDROID (SoftRight, AKEYCODE_SOFT_RIGHT)
 #undef KEY_MAP_COCOA
 #undef KEY_MAP_GTK
 #undef KEY_MAP_ANDROID
+#undef KEY_MAP_ANDROID_EXCEPT_B2G
+#undef KEY_MAP_B2G