diff --git a/engine/bindings/core/v8/V8AbstractEventListener.cpp b/engine/bindings/core/v8/V8AbstractEventListener.cpp
index e023575972d..2d862a0985d 100644
--- a/engine/bindings/core/v8/V8AbstractEventListener.cpp
+++ b/engine/bindings/core/v8/V8AbstractEventListener.cpp
@@ -37,7 +37,6 @@
 #include "bindings/core/v8/V8EventTarget.h"
 #include "bindings/core/v8/V8HiddenValue.h"
 #include "core/dom/Document.h"
-#include "core/events/BeforeUnloadEvent.h"
 #include "core/events/Event.h"
 #include "core/inspector/InspectorCounters.h"
 
@@ -141,11 +140,6 @@ void V8AbstractEventListener::invokeEventHandler(Event* event, v8::Local<v8::Val
     if (returnValue.IsEmpty())
         return;
 
-    if (m_isAttribute && !returnValue->IsNull() && !returnValue->IsUndefined() && event->isBeforeUnloadEvent()) {
-        TOSTRING_VOID(V8StringResource<>, stringReturnValue, returnValue);
-        toBeforeUnloadEvent(event)->setReturnValue(stringReturnValue);
-    }
-
     if (m_isAttribute && shouldPreventDefault(returnValue))
         event->preventDefault();
 }
diff --git a/engine/core/core.gni b/engine/core/core.gni
index 1f395065aa9..bcf15cd31e4 100644
--- a/engine/core/core.gni
+++ b/engine/core/core.gni
@@ -619,8 +619,6 @@ sky_core_files = [
   "events/AnimationPlayerEvent.h",
   "events/BeforeTextInsertedEvent.cpp",
   "events/BeforeTextInsertedEvent.h",
-  "events/BeforeUnloadEvent.cpp",
-  "events/BeforeUnloadEvent.h",
   "events/CompositionEvent.cpp",
   "events/CompositionEvent.h",
   "events/CustomEvent.cpp",
@@ -1289,7 +1287,6 @@ core_idl_files = get_path_info([
   "dom/shadow/ShadowRoot.idl",
   "editing/Selection.idl",
   "events/AnimationPlayerEvent.idl",
-  "events/BeforeUnloadEvent.idl",
   "events/CompositionEvent.idl",
   "events/CustomEvent.idl",
   "events/ErrorEvent.idl",
@@ -1411,7 +1408,6 @@ core_event_idl_files = get_path_info([
   "css/FontFaceSetLoadEvent.idl",
   "css/MediaQueryListEvent.idl",
   "events/AnimationPlayerEvent.idl",
-  "events/BeforeUnloadEvent.idl",
   "events/CompositionEvent.idl",
   "events/CustomEvent.idl",
   "events/ErrorEvent.idl",
diff --git a/engine/core/dom/Document.cpp b/engine/core/dom/Document.cpp
index d2130e7755e..fbce9f2115a 100644
--- a/engine/core/dom/Document.cpp
+++ b/engine/core/dom/Document.cpp
@@ -83,7 +83,6 @@
 #include "core/editing/FrameSelection.h"
 #include "core/editing/SpellChecker.h"
 #include "core/editing/markup.h"
-#include "core/events/BeforeUnloadEvent.h"
 #include "core/events/Event.h"
 #include "core/events/EventFactory.h"
 #include "core/events/EventListener.h"
@@ -1617,8 +1616,6 @@ void Document::dispatchUnloadEvents()
 
 Document::PageDismissalType Document::pageDismissalEventBeingDispatched() const
 {
-    if (m_loadEventProgress == BeforeUnloadEventInProgress)
-        return BeforeUnloadDismissal;
     if (m_loadEventProgress == PageHideInProgress)
         return PageHideDismissal;
     if (m_loadEventProgress == UnloadEventInProgress)
diff --git a/engine/core/dom/Document.h b/engine/core/dom/Document.h
index 495a5028e34..42547dae151 100644
--- a/engine/core/dom/Document.h
+++ b/engine/core/dom/Document.h
@@ -361,7 +361,6 @@ public:
 
     enum PageDismissalType {
         NoDismissal = 0,
-        BeforeUnloadDismissal = 1,
         PageHideDismissal = 2,
         UnloadDismissal = 3
     };
@@ -574,8 +573,6 @@ public:
         LoadEventTried,
         LoadEventInProgress,
         LoadEventCompleted,
-        BeforeUnloadEventInProgress,
-        BeforeUnloadEventCompleted,
         PageHideInProgress,
         UnloadEventInProgress,
         UnloadEventHandled
diff --git a/engine/core/events/BeforeUnloadEvent.cpp b/engine/core/events/BeforeUnloadEvent.cpp
deleted file mode 100644
index 32d19e178e5..00000000000
--- a/engine/core/events/BeforeUnloadEvent.cpp
+++ /dev/null
@@ -1,50 +0,0 @@
-/*
- * Copyright (C) 2001 Peter Kelly (pmk@post.com)
- * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
- * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
- * Copyright (C) 2003, 2005, 2006 Apple Computer, Inc.
- * Copyright (C) 2013 Samsung Electronics.
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public License
- * along with this library; see the file COPYING.LIB.  If not, write to
- * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
- * Boston, MA 02110-1301, USA.
- */
-
-#include "config.h"
-#include "core/events/BeforeUnloadEvent.h"
-
-
-namespace blink {
-
-BeforeUnloadEvent::BeforeUnloadEvent()
-    : Event(EventTypeNames::beforeunload, false, true)
-{
-    ScriptWrappable::init(this);
-}
-
-BeforeUnloadEvent::~BeforeUnloadEvent()
-{
-}
-
-bool BeforeUnloadEvent::isBeforeUnloadEvent() const
-{
-    return true;
-}
-
-void BeforeUnloadEvent::trace(Visitor* visitor)
-{
-    Event::trace(visitor);
-}
-
-} // namespace blink
diff --git a/engine/core/events/BeforeUnloadEvent.h b/engine/core/events/BeforeUnloadEvent.h
deleted file mode 100644
index ef7dedd5a6d..00000000000
--- a/engine/core/events/BeforeUnloadEvent.h
+++ /dev/null
@@ -1,61 +0,0 @@
-/*
- * Copyright (C) 2001 Peter Kelly (pmk@post.com)
- * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
- * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
- * Copyright (C) 2003, 2004, 2005, 2006 Apple Computer, Inc.
- * Copyright (C) 2013 Samsung Electronics.
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public License
- * along with this library; see the file COPYING.LIB.  If not, write to
- * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
- * Boston, MA 02110-1301, USA.
- *
- */
-
-#ifndef BeforeUnloadEvent_h
-#define BeforeUnloadEvent_h
-
-#include "core/events/Event.h"
-
-namespace blink {
-
-class BeforeUnloadEvent FINAL : public Event {
-    DEFINE_WRAPPERTYPEINFO();
-public:
-    virtual ~BeforeUnloadEvent();
-
-    static PassRefPtrWillBeRawPtr<BeforeUnloadEvent> create()
-    {
-        return adoptRefWillBeNoop(new BeforeUnloadEvent);
-    }
-
-    virtual bool isBeforeUnloadEvent() const OVERRIDE;
-
-    void setReturnValue(const String& returnValue) { m_returnValue = returnValue; }
-    String returnValue() const { return m_returnValue; }
-
-    virtual const AtomicString& interfaceName() const OVERRIDE { return EventNames::BeforeUnloadEvent; }
-
-    virtual void trace(Visitor*) OVERRIDE;
-
-private:
-    BeforeUnloadEvent();
-
-    String m_returnValue;
-};
-
-DEFINE_EVENT_TYPE_CASTS(BeforeUnloadEvent);
-
-} // namespace blink
-
-#endif // BeforeUnloadEvent_h
diff --git a/engine/core/events/BeforeUnloadEvent.idl b/engine/core/events/BeforeUnloadEvent.idl
deleted file mode 100644
index 618d5580939..00000000000
--- a/engine/core/events/BeforeUnloadEvent.idl
+++ /dev/null
@@ -1,33 +0,0 @@
-/*
- * Copyright (C) 2013 Samsung Electronics. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-interface BeforeUnloadEvent : Event {
-    attribute DOMString returnValue;
-};
diff --git a/engine/core/events/Event.cpp b/engine/core/events/Event.cpp
index e63a237857f..9765f3b0212 100644
--- a/engine/core/events/Event.cpp
+++ b/engine/core/events/Event.cpp
@@ -188,11 +188,6 @@ bool Event::isBeforeTextInsertedEvent() const
     return false;
 }
 
-bool Event::isBeforeUnloadEvent() const
-{
-    return false;
-}
-
 void Event::setTarget(PassRefPtrWillBeRawPtr<EventTarget> target)
 {
     if (m_target == target)
diff --git a/engine/core/events/Event.h b/engine/core/events/Event.h
index 4b1143bccda..57a1d83312a 100644
--- a/engine/core/events/Event.h
+++ b/engine/core/events/Event.h
@@ -154,8 +154,6 @@ public:
     virtual bool isClipboardEvent() const;
     virtual bool isBeforeTextInsertedEvent() const;
 
-    virtual bool isBeforeUnloadEvent() const;
-
     bool propagationStopped() const { return m_propagationStopped || m_immediatePropagationStopped; }
     bool immediatePropagationStopped() const { return m_immediatePropagationStopped; }
 
diff --git a/engine/core/events/EventTarget.cpp b/engine/core/events/EventTarget.cpp
index 17f7b0b4ea1..c4ff0cb7d3f 100644
--- a/engine/core/events/EventTarget.cpp
+++ b/engine/core/events/EventTarget.cpp
@@ -289,10 +289,7 @@ void EventTarget::fireEventListeners(Event* event, EventTargetData* d, EventList
     // index |size|, so iterating up to (but not including) |size| naturally excludes
     // new event listeners.
 
-    if (event->type() == EventTypeNames::beforeunload) {
-        if (LocalDOMWindow* executingWindow = this->executingWindow())
-            UseCounter::count(executingWindow->document(), UseCounter::DocumentBeforeUnloadFired);
-    } else if (event->type() == EventTypeNames::unload) {
+    if (event->type() == EventTypeNames::unload) {
         if (LocalDOMWindow* executingWindow = this->executingWindow())
             UseCounter::count(executingWindow->document(), UseCounter::DocumentUnloadFired);
     } else if (event->type() == EventTypeNames::DOMFocusIn || event->type() == EventTypeNames::DOMFocusOut) {
diff --git a/engine/core/events/EventTypeNames.in b/engine/core/events/EventTypeNames.in
index 513d0dc6232..18966e3bf42 100644
--- a/engine/core/events/EventTypeNames.in
+++ b/engine/core/events/EventTypeNames.in
@@ -26,7 +26,6 @@ autocompleteerror
 beforecopy
 beforecut
 beforepaste
-beforeunload
 beginEvent
 blocked
 blur
diff --git a/engine/core/frame/DOMWindowEventHandlers.h b/engine/core/frame/DOMWindowEventHandlers.h
index 8b0b5abdb3d..b7cae609829 100644
--- a/engine/core/frame/DOMWindowEventHandlers.h
+++ b/engine/core/frame/DOMWindowEventHandlers.h
@@ -35,7 +35,6 @@
 namespace blink {
 
 namespace DOMWindowEventHandlers {
-DEFINE_STATIC_WINDOW_ATTRIBUTE_EVENT_LISTENER(beforeunload);
 DEFINE_STATIC_WINDOW_ATTRIBUTE_EVENT_LISTENER(hashchange);
 DEFINE_STATIC_WINDOW_ATTRIBUTE_EVENT_LISTENER(languagechange);
 DEFINE_STATIC_WINDOW_ATTRIBUTE_EVENT_LISTENER(message);
diff --git a/engine/core/frame/LocalDOMWindow.cpp b/engine/core/frame/LocalDOMWindow.cpp
index ec0b93616e9..9a3871b94cf 100644
--- a/engine/core/frame/LocalDOMWindow.cpp
+++ b/engine/core/frame/LocalDOMWindow.cpp
@@ -112,12 +112,6 @@ static DOMWindowSet& windowsWithUnloadEventListeners()
     return windowsWithUnloadEventListeners;
 }
 
-static DOMWindowSet& windowsWithBeforeUnloadEventListeners()
-{
-    DEFINE_STATIC_LOCAL(DOMWindowSet, windowsWithBeforeUnloadEventListeners, ());
-    return windowsWithBeforeUnloadEventListeners;
-}
-
 static void addUnloadEventListener(LocalDOMWindow* domWindow)
 {
     DOMWindowSet& set = windowsWithUnloadEventListeners();
@@ -148,42 +142,6 @@ static void removeAllUnloadEventListeners(LocalDOMWindow* domWindow)
         enableSuddenTermination();
 }
 
-static void addBeforeUnloadEventListener(LocalDOMWindow* domWindow)
-{
-    DOMWindowSet& set = windowsWithBeforeUnloadEventListeners();
-    if (set.isEmpty())
-        disableSuddenTermination();
-    set.add(domWindow);
-}
-
-static void removeBeforeUnloadEventListener(LocalDOMWindow* domWindow)
-{
-    DOMWindowSet& set = windowsWithBeforeUnloadEventListeners();
-    DOMWindowSet::iterator it = set.find(domWindow);
-    if (it == set.end())
-        return;
-    set.remove(it);
-    if (set.isEmpty())
-        enableSuddenTermination();
-}
-
-static void removeAllBeforeUnloadEventListeners(LocalDOMWindow* domWindow)
-{
-    DOMWindowSet& set = windowsWithBeforeUnloadEventListeners();
-    DOMWindowSet::iterator it = set.find(domWindow);
-    if (it == set.end())
-        return;
-    set.removeAll(it);
-    if (set.isEmpty())
-        enableSuddenTermination();
-}
-
-static bool allowsBeforeUnloadListeners(LocalDOMWindow* window)
-{
-    ASSERT_ARG(window, window);
-    return window->frame();
-}
-
 unsigned LocalDOMWindow::pendingUnloadEventListeners() const
 {
     return windowsWithUnloadEventListeners().count(const_cast<LocalDOMWindow*>(this));
@@ -855,19 +813,7 @@ bool LocalDOMWindow::addEventListener(const AtomicString& eventType, PassRefPtr<
     if (eventType == EventTypeNames::unload) {
         UseCounter::count(document(), UseCounter::DocumentUnloadRegistered);
         addUnloadEventListener(this);
-    } else if (eventType == EventTypeNames::beforeunload) {
-        UseCounter::count(document(), UseCounter::DocumentBeforeUnloadRegistered);
-        if (allowsBeforeUnloadListeners(this)) {
-            // This is confusingly named. It doesn't actually add the listener. It just increments a count
-            // so that we know we have listeners registered for the purposes of determining if we can
-            // fast terminate the renderer process.
-            addBeforeUnloadEventListener(this);
-        } else {
-            // Subframes return false from allowsBeforeUnloadListeners.
-            UseCounter::count(document(), UseCounter::SubFrameBeforeUnloadRegistered);
-        }
     }
-
     return true;
 }
 
@@ -883,8 +829,6 @@ bool LocalDOMWindow::removeEventListener(const AtomicString& eventType, PassRefP
 
     if (eventType == EventTypeNames::unload) {
         removeUnloadEventListener(this);
-    } else if (eventType == EventTypeNames::beforeunload && allowsBeforeUnloadListeners(this)) {
-        removeBeforeUnloadEventListener(this);
     }
 
     return true;
@@ -928,7 +872,6 @@ void LocalDOMWindow::removeAllEventListenersInternal(BroadcastListenerRemoval mo
     }
 
     removeAllUnloadEventListeners(this);
-    removeAllBeforeUnloadEventListeners(this);
 }
 
 void LocalDOMWindow::removeAllEventListeners()
diff --git a/engine/core/frame/UseCounter.h b/engine/core/frame/UseCounter.h
index 4ffe5e1da15..2aab8ca57b3 100644
--- a/engine/core/frame/UseCounter.h
+++ b/engine/core/frame/UseCounter.h
@@ -121,8 +121,6 @@ public:
         SVGAnimationElement = 90,
         KeyboardEventKeyLocation = 91,
         LineClamp = 96,
-        SubFrameBeforeUnloadRegistered = 97,
-        SubFrameBeforeUnloadFired = 98,
         TextReplaceWholeText = 100,
         ConsoleMarkTimeline = 102,
         CSSPseudoElementUserAgentCustomPseudo = 103,
@@ -185,8 +183,6 @@ public:
         InputTypePasswordMaxLength = 193,
         PrefixedPageVisibility = 196,
         CSSStyleSheetInsertRuleOptionalArg = 198, // Inconsistent with the specification and other browsers.
-        DocumentBeforeUnloadRegistered = 200,
-        DocumentBeforeUnloadFired = 201,
         DocumentUnloadRegistered = 202,
         DocumentUnloadFired = 203,
         SVGLocatableNearestViewportElement = 204,
diff --git a/engine/core/frame/WindowEventHandlers.idl b/engine/core/frame/WindowEventHandlers.idl
index 95de525822a..594fdbc1f7b 100644
--- a/engine/core/frame/WindowEventHandlers.idl
+++ b/engine/core/frame/WindowEventHandlers.idl
@@ -36,7 +36,6 @@
 ] interface WindowEventHandlers {
     //attribute EventHandler onafterprint;
     //attribute EventHandler onbeforeprint;
-    attribute EventHandler onbeforeunload;
     attribute EventHandler onhashchange;
     attribute EventHandler onlanguagechange;
     attribute EventHandler onmessage;