diff --git a/browser/components/places/content/controller.js b/browser/components/places/content/controller.js
index f48aea85183a..ebe3c4d584f2 100755
--- a/browser/components/places/content/controller.js
+++ b/browser/components/places/content/controller.js
@@ -1327,6 +1327,56 @@ var PlacesController = {
    * See: https://bugzilla.mozilla.org/show_bug.cgi?id=331908
    */
   openLinksInTabs: function PC_openLinksInTabs() {
+    var pref = 
+        Components.classes["@mozilla.org/preferences-service;1"].
+        getService(Components.interfaces.nsIPrefBranch);
+
+    const kWarnOnOpenPref = "browser.tabs.warnOnOpen";
+    if (pref.getBoolPref(kWarnOnOpenPref))
+    {
+      var reallyOpen = true;
+
+      // determine how many tabs we are attempting to open
+      var node = this._activeView.selectedNode;
+      asFolder(node);
+      var wasOpen = node.containerOpen;
+      node.containerOpen = true;
+      var tabsToOpen = node.childCount;
+      node.containerOpen = wasOpen;
+
+      if (tabsToOpen >= pref.getIntPref("browser.tabs.maxOpenBeforeWarn"))
+      {
+        var promptService =
+            Components.classes["@mozilla.org/embedcomp/prompt-service;1"].
+            getService(Components.interfaces.nsIPromptService);
+
+        // default to true: if it were false, we wouldn't get this far
+        var warnOnOpen = { value: true };
+
+        var messageKey = "tabs.openWarningMultiple";
+        var openKey = "tabs.openButtonMultiple";
+        var strings = document.getElementById("placeBundle");
+        
+        var buttonPressed = promptService.confirmEx(window,
+            strings.getString("tabs.openWarningTitle"),
+            strings.getFormattedString(messageKey, [tabsToOpen]),
+            (promptService.BUTTON_TITLE_IS_STRING * promptService.BUTTON_POS_0)
+            + (promptService.BUTTON_TITLE_CANCEL * promptService.BUTTON_POS_1),
+            strings.getString(openKey),
+            null, null,
+            strings.getString("tabs.openWarningPromptMe"),
+            warnOnOpen);
+
+         reallyOpen = (buttonPressed == 0);
+         // don't set the pref unless they press OK and it's false
+         if (reallyOpen && !warnOnOpen.value)
+           pref.setBoolPref(kWarnOnOpen, false);
+       }
+
+       if (!reallyOpen)
+         return;
+    }
+
     var node = this._activeView.selectedNode;
     if (this._activeView.hasSingleSelection && this.nodeIsFolder(node)) {
       // Check prefs to see whether to open over existing tabs.
diff --git a/browser/components/preferences/tabs.xul b/browser/components/preferences/tabs.xul
index 7144d3eb3f16..099a09aa84fb 100644
--- a/browser/components/preferences/tabs.xul
+++ b/browser/components/preferences/tabs.xul
@@ -55,6 +55,7 @@
       <preference id="browser.tabs.autoHide"           name="browser.tabs.autoHide"           type="bool"/>
       <preference id="browser.tabs.loadInBackground"   name="browser.tabs.loadInBackground"   type="bool" inverted="true"/>
       <preference id="browser.tabs.warnOnClose"        name="browser.tabs.warnOnClose"        type="bool"/>
+      <preference id="browser.tabs.warnOnOpen"         name="browser.tabs.warnOnOpen"         type="bool"/>
     </preferences>
     
     <script type="application/x-javascript" src="chrome://browser/content/preferences/tabs.js"/>
@@ -79,6 +80,9 @@
       <checkbox id="warnOnClose" label="&warnOnClose.label;"
                 accesskey="&warnOnClose.accesskey;"
                 preference="browser.tabs.warnOnClose"/>
+      <checkbox id="warnOnOpen" label="&warnOnOpen.label;"
+                accesskey="&warnOnOpen.accesskey;"
+                preference="browser.tabs.warnOnOpen"/>
     </vbox>
   </prefpane>
 
diff --git a/browser/locales/en-US/chrome/browser/places/places.properties b/browser/locales/en-US/chrome/browser/places/places.properties
index b19c60cb28d6..eb6c359a9b14 100644
--- a/browser/locales/en-US/chrome/browser/places/places.properties
+++ b/browser/locales/en-US/chrome/browser/places/places.properties
@@ -63,3 +63,8 @@ sortByPrefix=Sort by %S
 searchDefault=Search in Bookmarks & History
 searchCurrentDefault=Search in '%S'
 findInPrefix=Find in '%S'...
+
+tabs.openWarningTitle=Confirm open
+tabs.openWarningMultiple=You have asked to open %S tabs at once. This might slow down your system while the pages are loading.
+tabs.openButtonMultiple=Open tabs
+tabs.openWarningPromptMe=Warn me when I attempt to open a lot of tabs at once
diff --git a/browser/locales/en-US/chrome/browser/preferences/tabs.dtd b/browser/locales/en-US/chrome/browser/preferences/tabs.dtd
index 4349472a6f07..9c1456a26ba2 100644
--- a/browser/locales/en-US/chrome/browser/preferences/tabs.dtd
+++ b/browser/locales/en-US/chrome/browser/preferences/tabs.dtd
@@ -11,5 +11,9 @@
 <!ENTITY loadInBackground.accesskey          "l">
 <!ENTITY loadBookmarksInBackground.label     "Select new tabs opened from bookmarks or history">
 <!ENTITY loadBookmarksInBackground.accesskey "b">
+
 <!ENTITY warnOnClose.label                   "Warn when closing multiple tabs">
 <!ENTITY warnOnClose.accesskey               "m">
+
+<!ENTITY warnOnOpen.label                    "Warn when opening a lot of tabs at once">
+<!ENTITY warnOnOpen.accesskey                "o">
diff --git a/modules/libpref/src/init/all.js b/modules/libpref/src/init/all.js
index 5376445b37b6..62445a739a74 100644
--- a/modules/libpref/src/init/all.js
+++ b/modules/libpref/src/init/all.js
@@ -153,6 +153,8 @@ pref("browser.tabs.autoHide", true);
 pref("browser.tabs.forceHide", false);
 pref("browser.tabs.warnOnClose", true);
 pref("browser.tabs.warnOnCloseOther", true);
+pref("browser.tabs.warnOnOpen", true);
+pref("browser.tabs.maxOpenBeforeWarn", 15);
 // 0 = append, 1 = replace
 pref("browser.tabs.loadGroup", 1);