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diff --git a/Source/WTF/wtf/win/WorkQueueWin.cpp b/Source/WTF/wtf/win/WorkQueueWin.cpp
new file mode 100644
index 000000000..6e61cde69
--- /dev/null
+++ b/Source/WTF/wtf/win/WorkQueueWin.cpp
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+/*
+* Copyright (C) 2010, 2015 Apple Inc. All rights reserved.
+*
+* Redistribution and use in source and binary forms, with or without
+* modification, are permitted provided that the following conditions
+* are met:
+* 1. Redistributions of source code must retain the above copyright
+*    notice, this list of conditions and the following disclaimer.
+* 2. 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.
+*
+* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS 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 APPLE INC. OR ITS 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.
+*/
+
+#include "config.h"
+#include "WorkQueue.h"
+
+#include <wtf/MathExtras.h>
+#include <wtf/Threading.h>
+#include <wtf/win/WorkItemWin.h>
+
+namespace WTF {
+
+void WorkQueue::handleCallback(void* context, BOOLEAN timerOrWaitFired)
+{
+    ASSERT_ARG(context, context);
+    ASSERT_ARG(timerOrWaitFired, !timerOrWaitFired);
+
+    WorkItemWin* item = static_cast<WorkItemWin*>(context);
+    RefPtr<WorkQueue> queue = item->queue();
+
+    {
+        MutexLocker lock(queue->m_workItemQueueLock);
+        queue->m_workItemQueue.append(item);
+
+        // If no other thread is performing work, we can do it on this thread.
+        if (!queue->tryRegisterAsWorkThread()) {
+            // Some other thread is performing work. Since we hold the queue lock, we can be sure
+            // that the work thread is not exiting due to an empty queue and will process the work
+            // item we just added to it. If we weren't holding the lock we'd have to signal
+            // m_performWorkEvent to make sure the work item got picked up.
+            return;
+        }
+    }
+
+    queue->performWorkOnRegisteredWorkThread();
+}
+
+DWORD WorkQueue::workThreadCallback(void* context)
+{
+    ASSERT_ARG(context, context);
+
+    WorkQueue* queue = static_cast<WorkQueue*>(context);
+
+    if (!queue->tryRegisterAsWorkThread())
+        return 0;
+
+    queue->performWorkOnRegisteredWorkThread();
+    return 0;
+}
+
+void WorkQueue::performWorkOnRegisteredWorkThread()
+{
+    ASSERT(m_isWorkThreadRegistered);
+
+    m_workItemQueueLock.lock();
+
+    while (!m_workItemQueue.isEmpty()) {
+        Vector<RefPtr<WorkItemWin>> workItemQueue;
+        m_workItemQueue.swap(workItemQueue);
+
+        // Allow more work to be scheduled while we're not using the queue directly.
+        m_workItemQueueLock.unlock();
+        for (auto& workItem : workItemQueue) {
+            workItem->function()();
+            deref();
+        }
+        m_workItemQueueLock.lock();
+    }
+
+    // One invariant we maintain is that any work scheduled while a work thread is registered will
+    // be handled by that work thread. Unregister as the work thread while the queue lock is still
+    // held so that no work can be scheduled while we're still registered.
+    unregisterAsWorkThread();
+
+    m_workItemQueueLock.unlock();
+}
+
+void WorkQueue::platformInitialize(const char* name, Type, QOS)
+{
+    m_isWorkThreadRegistered = 0;
+    m_timerQueue = ::CreateTimerQueue();
+    ASSERT_WITH_MESSAGE(m_timerQueue, "::CreateTimerQueue failed with error %lu", ::GetLastError());
+}
+
+bool WorkQueue::tryRegisterAsWorkThread()
+{
+    LONG result = ::InterlockedCompareExchange(&m_isWorkThreadRegistered, 1, 0);
+    ASSERT(!result || result == 1);
+    return !result;
+}
+
+void WorkQueue::unregisterAsWorkThread()
+{
+    LONG result = ::InterlockedCompareExchange(&m_isWorkThreadRegistered, 0, 1);
+    ASSERT_UNUSED(result, result == 1);
+}
+
+void WorkQueue::platformInvalidate()
+{
+#if !ASSERT_DISABLED
+    MutexLocker lock(m_handlesLock);
+    ASSERT(m_handles.isEmpty());
+#endif
+
+    // FIXME: We need to ensure that any timer-queue timers that fire after this point don't try to
+    // access this WorkQueue <http://webkit.org/b/44690>.
+    ::DeleteTimerQueueEx(m_timerQueue, 0);
+}
+
+void WorkQueue::dispatch(std::function<void()> function)
+{
+    MutexLocker locker(m_workItemQueueLock);
+    ref();
+    m_workItemQueue.append(WorkItemWin::create(function, this));
+
+    // Spawn a work thread to perform the work we just added. As an optimization, we avoid
+    // spawning the thread if a work thread is already registered. This prevents multiple work
+    // threads from being spawned in most cases. (Note that when a work thread has been spawned but
+    // hasn't registered itself yet, m_isWorkThreadRegistered will be false and we'll end up
+    // spawning a second work thread here. But work thread registration process will ensure that
+    // only one thread actually ends up performing work.)
+    if (!m_isWorkThreadRegistered)
+        ::QueueUserWorkItem(workThreadCallback, this, WT_EXECUTEDEFAULT);
+}
+
+struct TimerContext : public ThreadSafeRefCounted<TimerContext> {
+    static RefPtr<TimerContext> create() { return adoptRef(new TimerContext); }
+
+    WorkQueue* queue;
+    std::function<void()> function;
+    Mutex timerMutex;
+    HANDLE timer;
+
+private:
+    TimerContext()
+        : queue(nullptr)
+        , timer(0)
+    {
+    }
+};
+
+void WorkQueue::timerCallback(void* context, BOOLEAN timerOrWaitFired)
+{
+    ASSERT_ARG(context, context);
+    ASSERT_UNUSED(timerOrWaitFired, timerOrWaitFired);
+
+    // Balanced by leakRef in scheduleWorkAfterDelay.
+    RefPtr<TimerContext> timerContext = adoptRef(static_cast<TimerContext*>(context));
+
+    timerContext->queue->dispatch(timerContext->function);
+
+    MutexLocker lock(timerContext->timerMutex);
+    ASSERT(timerContext->timer);
+    ASSERT(timerContext->queue->m_timerQueue);
+    if (!::DeleteTimerQueueTimer(timerContext->queue->m_timerQueue, timerContext->timer, 0)) {
+        // Getting ERROR_IO_PENDING here means that the timer will be destroyed once the callback is done executing.
+        ASSERT_WITH_MESSAGE(::GetLastError() == ERROR_IO_PENDING, "::DeleteTimerQueueTimer failed with error %lu", ::GetLastError());
+    }
+}
+
+void WorkQueue::dispatchAfter(std::chrono::nanoseconds duration, std::function<void()> function)
+{
+    ASSERT(m_timerQueue);
+    ref();
+
+    RefPtr<TimerContext> context = TimerContext::create();
+    context->queue = this;
+    context->function = function;
+
+    {
+        // The timer callback could fire before ::CreateTimerQueueTimer even returns, so we protect
+        // context->timer with a mutex to ensure the timer callback doesn't access it before the
+        // timer handle has been stored in it.
+        MutexLocker lock(context->timerMutex);
+
+        int64_t milliseconds = std::chrono::duration_cast<std::chrono::milliseconds>(duration).count();
+
+        // From empirical testing, we've seen CreateTimerQueueTimer() sometimes fire up to 5+ ms early.
+        // This causes havoc for clients of this code that expect to not be called back until the
+        // specified duration has expired. Other folks online have also observed some slop in the
+        // firing times of CreateTimerQuqueTimer(). From the data posted at
+        // http://omeg.pl/blog/2011/11/on-winapi-timers-and-their-resolution, it appears that the slop
+        // can be up to about 10 ms. To ensure that we don't fire the timer early, we'll tack on a
+        // slop adjustment to the duration, and we'll use double the worst amount of slop observed
+        // so far.
+        const int64_t slopAdjustment = 20;
+        if (milliseconds) 
+            milliseconds += slopAdjustment;
+
+        // Since our timer callback is quick, we can execute in the timer thread itself and avoid
+        // an extra thread switch over to a worker thread.
+        if (!::CreateTimerQueueTimer(&context->timer, m_timerQueue, timerCallback, context.get(), clampTo<DWORD>(milliseconds), 0, WT_EXECUTEINTIMERTHREAD)) {
+            ASSERT_WITH_MESSAGE(false, "::CreateTimerQueueTimer failed with error %lu", ::GetLastError());
+            return;
+        }
+    }
+
+    // The timer callback will handle destroying context.
+    context.release().leakRef();
+}
+
+void WorkQueue::unregisterWaitAndDestroyItemSoon(PassRefPtr<HandleWorkItem> item)
+{
+    // We're going to make a blocking call to ::UnregisterWaitEx before closing the handle. (The
+    // blocking version of ::UnregisterWaitEx is much simpler than the non-blocking version.) If we
+    // do this on the current thread, we'll deadlock if we're currently in a callback function for
+    // the wait we're unregistering. So instead we do it asynchronously on some other worker thread.
+
+    ::QueueUserWorkItem(unregisterWaitAndDestroyItemCallback, item.leakRef(), WT_EXECUTEDEFAULT);
+}
+
+DWORD WINAPI WorkQueue::unregisterWaitAndDestroyItemCallback(void* context)
+{
+    ASSERT_ARG(context, context);
+    RefPtr<HandleWorkItem> item = adoptRef(static_cast<HandleWorkItem*>(context));
+
+    // Now that we know we're not in a callback function for the wait we're unregistering, we can
+    // make a blocking call to ::UnregisterWaitEx.
+    if (!::UnregisterWaitEx(item->waitHandle(), INVALID_HANDLE_VALUE)) {
+        DWORD error = ::GetLastError();
+        ASSERT_NOT_REACHED();
+    }
+
+    return 0;
+}
+
+#if PLATFORM(QT)
+void WorkQueue::registerHandle(HANDLE handle, const std::function<void()>& function)
+{
+    RefPtr<HandleWorkItem> handleItem = HandleWorkItem::createByAdoptingHandle(handle, function, this);
+
+    {
+        MutexLocker lock(m_handlesLock);
+        ASSERT_ARG(handle, !m_handles.contains(handle));
+        m_handles.set(handle, handleItem);
+    }
+
+    HANDLE waitHandle;
+    if (!::RegisterWaitForSingleObject(&waitHandle, handle, handleCallback, handleItem.get(), INFINITE, WT_EXECUTEDEFAULT)) {
+        DWORD error = ::GetLastError();
+        ASSERT_NOT_REACHED();
+    }
+    handleItem->setWaitHandle(waitHandle);
+}
+
+void WorkQueue::unregisterAndCloseHandle(HANDLE handle)
+{
+    RefPtr<HandleWorkItem> item;
+    {
+        MutexLocker locker(m_handlesLock);
+        ASSERT_ARG(handle, m_handles.contains(handle));
+        item = m_handles.take(handle);
+    }
+
+    unregisterWaitAndDestroyItemSoon(item.release());
+}
+#endif
+
+} // namespace WTF