--- a/browser/base/content/browser-menubar.inc
+++ b/browser/base/content/browser-menubar.inc
@@ -447,16 +447,29 @@
         <menupopup id="otherBookmarksFolderPopup"
 #ifndef XP_MACOSX
                    placespopup="true"
 #endif
                    context="placesContext"
                    onpopupshowing="if (!this.parentNode._placesView)
                                      new PlacesMenu(event, 'place:folder=UNFILED_BOOKMARKS');"/>
       </menu>
+      <menu id="menu_mobileBookmarks"
+            class="menu-iconic bookmark-item"
+            label="&mobileBookmarksCmd.label;"
+            hidden="true"
+            container="true">
+        <menupopup id="mobileBookmarksFolderPopup"
+#ifndef XP_MACOSX
+                   placespopup="true"
+#endif
+                   context="placesContext"
+                   onpopupshowing="if (!this.parentNode._placesView)
+                                     new PlacesMenu(event, 'place:folder=MOBILE_BOOKMARKS');"/>
+      </menu>
       <menuseparator id="bookmarksMenuItemsSeparator"/>
       <!-- Bookmarks menu items -->
     </menupopup>
   </menu>
 
             <menu id="tools-menu"
                   label="&toolsMenu.label;"
                   accesskey="&toolsMenu.accesskey;"

--- a/browser/base/content/browser-places.js
+++ b/browser/base/content/browser-places.js
@@ -1313,16 +1313,17 @@ var BookmarkingUI = {
     if (widget.overflowed) {
       // Don't open a popup in the overflow popup, rather just open the Library.
       event.preventDefault();
       widget.node.removeAttribute("closemenu");
       PlacesCommandHook.showPlacesOrganizer("BookmarksMenu");
       return;
     }
 
+    this._initMobileBookmarks(document.getElementById("BMB_mobileBookmarks"));
     this._initRecentBookmarks(document.getElementById("BMB_recentBookmarks"),
                               "subviewbutton");
 
     if (!this._popupNeedsUpdate)
       return;
     this._popupNeedsUpdate = false;
 
     let popup = event.target;
@@ -1351,16 +1352,38 @@ var BookmarkingUI = {
         footer: "panel-subview-footer"
       },
       insertionPoint: ".panel-subview-footer"
     });
   },
 
   RECENTLY_BOOKMARKED_PREF: "browser.bookmarks.showRecentlyBookmarked",
 
+  // Set by sync after syncing bookmarks successfully once.
+  MOBILE_BOOKMARKS_PREF: "browser.bookmarks.showMobileBookmarks",
+
+  _shouldShowMobileBookmarks() {
+    try {
+      return Services.prefs.getBoolPref(this.MOBILE_BOOKMARKS_PREF);
+    } catch (e) {}
+    // No pref set (or invalid pref set), look for a mobile bookmarks left pane query.
+    const organizerQueryAnno = "PlacesOrganizer/OrganizerQuery";
+    const mobileBookmarksAnno = "MobileBookmarks";
+    let shouldShow = PlacesUtils.annotations.getItemsWithAnnotation(organizerQueryAnno, {}).filter(
+      id => PlacesUtils.annotations.getItemAnnotation(id, organizerQueryAnno) == mobileBookmarksAnno
+    ).length > 0;
+    // Sync will change this pref if/when it adds a mobile bookmarks query.
+    Services.prefs.setBoolPref(this.MOBILE_BOOKMARKS_PREF, shouldShow);
+    return shouldShow;
+  },
+
+  _initMobileBookmarks(mobileMenuItem) {
+    mobileMenuItem.hidden = !this._shouldShowMobileBookmarks();
+  },
+
   _initRecentBookmarks(aHeaderItem, aExtraCSSClass) {
     this._populateRecentBookmarks(aHeaderItem, aExtraCSSClass);
 
     // Add observers and listeners and remove them again when the menupopup closes.
 
     let bookmarksMenu = aHeaderItem.parentNode;
     let placesContextMenu = document.getElementById("placesContext");
 
@@ -1676,16 +1699,17 @@ var BookmarkingUI = {
 
   onMainMenuPopupShowing: function BUI_onMainMenuPopupShowing(event) {
     // Don't handle events for submenus.
     if (event.target != event.currentTarget)
       return;
 
     this._updateBookmarkPageMenuItem();
     PlacesCommandHook.updateBookmarkAllTabsCommand();
+    this._initMobileBookmarks(document.getElementById("menu_mobileBookmarks"));
     this._initRecentBookmarks(document.getElementById("menu_recentBookmarks"));
   },
 
   _showBookmarkedNotification: function BUI_showBookmarkedNotification() {
     function getCenteringTransformForRects(rectToPosition, referenceRect) {
       let topDiff = referenceRect.top - rectToPosition.top;
       let leftDiff = referenceRect.left - rectToPosition.left;
       let heightDiff = referenceRect.height - rectToPosition.height;

--- a/browser/base/content/browser.xul
+++ b/browser/base/content/browser.xul
@@ -877,16 +877,29 @@
                   container="true">
               <menupopup id="BMB_unsortedBookmarksPopup"
                          placespopup="true"
                          context="placesContext"
                          onpopupshowing="if (!this.parentNode._placesView)
                                            new PlacesMenu(event, 'place:folder=UNFILED_BOOKMARKS',
                                                           PlacesUIUtils.getViewForNode(this.parentNode.parentNode).options);"/>
             </menu>
+            <menu id="BMB_mobileBookmarks"
+                  class="menu-iconic bookmark-item subviewbutton"
+                  label="&bookmarksMenuButton.mobile.label;"
+                  hidden="true"
+                  container="true">
+              <menupopup id="BMB_mobileBookmarksPopup"
+                         placespopup="true"
+                         context="placesContext"
+                         onpopupshowing="if (!this.parentNode._placesView)
+                                           new PlacesMenu(event, 'place:folder=MOBILE_BOOKMARKS',
+                                                          PlacesUIUtils.getViewForNode(this.parentNode.parentNode).options);"/>
+            </menu>
+
             <menuseparator/>
             <!-- Bookmarks menu items will go here -->
             <menuitem id="BMB_bookmarksShowAll"
                       class="subviewbutton panel-subview-footer"
                       label="&showAllBookmarks2.label;"
                       command="Browser:ShowAllBookmarks"
                       key="manBookmarkKb"/>
           </menupopup>

--- a/browser/locales/en-US/chrome/browser/browser.dtd
+++ b/browser/locales/en-US/chrome/browser/browser.dtd
@@ -179,16 +179,17 @@ These should match what Safari and other
 <!ENTITY shareVideo.accesskey "r">
 <!ENTITY feedsMenu2.label "Subscribe to This Page">
 <!ENTITY subscribeToPageMenupopup.label "Subscribe to This Page">
 <!ENTITY subscribeToPageMenuitem.label "Subscribe to This Page…">
 <!ENTITY addCurPagesCmd.label "Bookmark All Tabs…">
 <!ENTITY showAllBookmarks2.label "Show All Bookmarks">
 <!ENTITY recentBookmarks.label "Recently Bookmarked">
 <!ENTITY otherBookmarksCmd.label "Other Bookmarks">
+<!ENTITY mobileBookmarksCmd.label "Mobile Bookmarks">
 <!ENTITY bookmarksToolbarChevron.tooltip "Show more bookmarks">
 <!ENTITY showRecentlyBookmarked.label     "Show Recently Bookmarked">
 <!ENTITY showRecentlyBookmarked.accesskey "h">
 <!ENTITY hideRecentlyBookmarked.label     "Hide Recently Bookmarked">
 <!ENTITY hideRecentlyBookmarked.accesskey "H">
 
 <!ENTITY backCmd.label                "Back">
 <!ENTITY backButton.tooltip           "Go back one page">
@@ -240,16 +241,17 @@ These should match what Safari and other
 <!-- Toolbar items --> 
 <!ENTITY homeButton.label             "Home">
 
 <!ENTITY bookmarksButton.label          "Bookmarks">
 <!ENTITY bookmarksCmd.commandkey "b">
 
 <!ENTITY bookmarksMenuButton.label          "Bookmarks">
 <!ENTITY bookmarksMenuButton.other.label "Other Bookmarks">
+<!ENTITY bookmarksMenuButton.mobile.label "Mobile Bookmarks">
 <!ENTITY viewBookmarksSidebar2.label        "View Bookmarks Sidebar">
 <!ENTITY viewBookmarksToolbar.label         "View Bookmarks Toolbar">
 
 <!ENTITY containersMenu.label "Containers">
 
 <!-- LOCALIZATION NOTE (bookmarksSidebarGtkCmd.commandkey): This command
   -  key should not contain the letters A-F, since these are reserved
   -  shortcut keys on Linux. -->

--- a/browser/themes/shared/customizableui/panelUI.inc.css
+++ b/browser/themes/shared/customizableui/panelUI.inc.css
@@ -1163,17 +1163,18 @@ menuitem.panel-subview-footer@menuStateA
   /* Hide bottom separator as the styled footer includes a top border serving the same purpose */
   display: none;
 }
 
 /* Popups with only one item don't have a footer */
 #BMB_bookmarksPopup menupopup[placespopup=true][singleitempopup=true] > hbox > .popup-internal-box > .arrowscrollbox-scrollbox > .scrollbox-innerbox,
 /* These popups never have a footer */
 #BMB_bookmarksToolbarPopup > hbox > .popup-internal-box > .arrowscrollbox-scrollbox > .scrollbox-innerbox,
-#BMB_unsortedBookmarksPopup > hbox > .popup-internal-box > .arrowscrollbox-scrollbox > .scrollbox-innerbox {
+#BMB_unsortedBookmarksPopup > hbox > .popup-internal-box > .arrowscrollbox-scrollbox > .scrollbox-innerbox,
+#BMB_mobileBookmarksPopup > hbox > .popup-internal-box > .arrowscrollbox-scrollbox > .scrollbox-innerbox {
   /* And so they need some bottom padding: */
   padding-bottom: 4px;
 }
 
 /* Disabled (empty) item is always alone and never has an icon, so fix its left padding */
 #BMB_bookmarksPopup menupopup[emptyplacesresult] .bookmark-item.subviewbutton {
   padding-left: 6px;
 }

--- a/services/sync/modules/engines/bookmarks.js
+++ b/services/sync/modules/engines/bookmarks.js
@@ -1024,16 +1024,17 @@ BookmarksTracker.prototype = {
       return;
     }
 
     this._log.trace("onItemRemoved: " + itemId);
     this._upScore();
   },
 
   _ensureMobileQuery: function _ensureMobileQuery() {
+    Services.prefs.setBoolPref("browser.bookmarks.showMobileBookmarks", true);
     let find = val =>
       PlacesUtils.annotations.getItemsWithAnnotation(ORGANIZERQUERY_ANNO, {}).filter(
         id => PlacesUtils.annotations.getItemAnnotation(id, ORGANIZERQUERY_ANNO) == val
       );
 
     // Don't continue if the Library isn't ready
     let all = find(ALLBOOKMARKS_ANNO);
     if (all.length == 0)