diff --git a/buffer_iocp.c b/buffer_iocp.c
new file mode 100644
index 0000000..5d5303e
--- /dev/null
+++ b/buffer_iocp.c
@@ -0,0 +1,325 @@
+/*
+ * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson
+ *
+ * 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.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
+ */
+
+/**
+   @file buffer_iocp.c
+
+   This module implements overlapped read and write functions for evbuffer
+   objects on Windows.
+*/
+
+#include "event2/buffer.h"
+#include "event2/buffer_compat.h"
+#include "event2/util.h"
+#include "event2/thread.h"
+#include "event2/event-config.h"
+#include "util-internal.h"
+#include "evthread-internal.h"
+#include "evbuffer-internal.h"
+#include "iocp-internal.h"
+#include "mm-internal.h"
+
+#include <winsock2.h>
+#include <windows.h>
+#include <stdio.h>
+
+#define MAX_WSABUFS 16
+
+/** An evbuffer that can handle overlapped IO. */
+struct evbuffer_overlapped {
+	struct evbuffer buffer;
+	/** The socket that we're doing overlapped IO on. */
+	evutil_socket_t fd;
+
+	/** pending I/O type */
+	unsigned read_in_progress : 1;
+	unsigned write_in_progress : 1;
+
+	/** The first pinned chain in the buffer. */
+	struct evbuffer_chain *first_pinned;
+
+	/** How many chains are pinned; how many of the fields in buffers
+	 * are we using. */
+	int n_buffers;
+	WSABUF buffers[MAX_WSABUFS];
+};
+
+/** Given an evbuffer, return the correponding evbuffer structure, or NULL if
+ * the evbuffer isn't overlapped. */
+static inline struct evbuffer_overlapped *
+upcast_evbuffer(struct evbuffer *buf)
+{
+	if (!buf || !buf->is_overlapped)
+		return NULL;
+	return EVUTIL_UPCAST(buf, struct evbuffer_overlapped, buffer);
+}
+
+/** Unpin all the chains noted as pinned in 'eo'. */
+static void
+pin_release(struct evbuffer_overlapped *eo, unsigned flag)
+{
+	int i;
+	struct evbuffer_chain *next, *chain = eo->first_pinned;
+
+	for (i = 0; i < eo->n_buffers; ++i) {
+		EVUTIL_ASSERT(chain);
+		next = chain->next;
+		_evbuffer_chain_unpin(chain, flag);
+		chain = next;
+	}
+}
+
+void
+evbuffer_commit_read(struct evbuffer *evbuf, ev_ssize_t nBytes)
+{
+	struct evbuffer_overlapped *buf = upcast_evbuffer(evbuf);
+	struct evbuffer_chain **chainp;
+	size_t remaining, len;
+	unsigned i;
+
+	EVBUFFER_LOCK(evbuf);
+	EVUTIL_ASSERT(buf->read_in_progress && !buf->write_in_progress);
+	EVUTIL_ASSERT(nBytes >= 0); /* XXXX Can this be false? */
+
+	evbuffer_unfreeze(evbuf, 0);
+
+	chainp = evbuf->last_with_datap;
+	if (!((*chainp)->flags & EVBUFFER_MEM_PINNED_R))
+		chainp = &(*chainp)->next;
+	remaining = nBytes;
+	for (i = 0; remaining > 0 && i < (unsigned)buf->n_buffers; ++i) {
+		EVUTIL_ASSERT(*chainp);
+		len = buf->buffers[i].len;
+		if (remaining < len)
+			len = remaining;
+		(*chainp)->off += len;
+		evbuf->last_with_datap = chainp;
+		remaining -= len;
+		chainp = &(*chainp)->next;
+	}
+
+	pin_release(buf, EVBUFFER_MEM_PINNED_R);
+
+	buf->read_in_progress = 0;
+
+	evbuf->total_len += nBytes;
+	evbuf->n_add_for_cb += nBytes;
+
+	evbuffer_invoke_callbacks(evbuf);
+
+	_evbuffer_decref_and_unlock(evbuf);
+}
+
+void
+evbuffer_commit_write(struct evbuffer *evbuf, ev_ssize_t nBytes)
+{
+	struct evbuffer_overlapped *buf = upcast_evbuffer(evbuf);
+
+	EVBUFFER_LOCK(evbuf);
+	EVUTIL_ASSERT(buf->write_in_progress && !buf->read_in_progress);
+	evbuffer_unfreeze(evbuf, 1);
+	evbuffer_drain(evbuf, nBytes);
+	pin_release(buf,EVBUFFER_MEM_PINNED_W);
+	buf->write_in_progress = 0;
+	_evbuffer_decref_and_unlock(evbuf);
+}
+
+struct evbuffer *
+evbuffer_overlapped_new(evutil_socket_t fd)
+{
+	struct evbuffer_overlapped *evo;
+
+	evo = mm_calloc(1, sizeof(struct evbuffer_overlapped));
+	if (!evo)
+		return NULL;
+
+	TAILQ_INIT(&evo->buffer.callbacks);
+	evo->buffer.refcnt = 1;
+	evo->buffer.last_with_datap = &evo->buffer.first;
+
+	evo->buffer.is_overlapped = 1;
+	evo->fd = fd;
+
+	return &evo->buffer;
+}
+
+int
+evbuffer_launch_write(struct evbuffer *buf, ev_ssize_t at_most,
+		struct event_overlapped *ol)
+{
+	struct evbuffer_overlapped *buf_o = upcast_evbuffer(buf);
+	int r = -1;
+	int i;
+	struct evbuffer_chain *chain;
+	DWORD bytesSent;
+
+	if (!buf) {
+		/* No buffer, or it isn't overlapped */
+		return -1;
+	}
+
+	EVBUFFER_LOCK(buf);
+	EVUTIL_ASSERT(!buf_o->read_in_progress);
+	if (buf->freeze_start || buf_o->write_in_progress)
+		goto done;
+	if (!buf->total_len) {
+		/* Nothing to write */
+		r = 0;
+		goto done;
+	} else if (at_most < 0 || (size_t)at_most > buf->total_len) {
+		at_most = buf->total_len;
+	}
+	evbuffer_freeze(buf, 1);
+
+	buf_o->first_pinned = NULL;
+	buf_o->n_buffers = 0;
+	memset(buf_o->buffers, 0, sizeof(buf_o->buffers));
+
+	chain = buf_o->first_pinned = buf->first;
+
+	for (i=0; i < MAX_WSABUFS && chain; ++i, chain=chain->next) {
+		WSABUF *b = &buf_o->buffers[i];
+		b->buf = (char*)( chain->buffer + chain->misalign );
+		_evbuffer_chain_pin(chain, EVBUFFER_MEM_PINNED_W);
+
+		if ((size_t)at_most > chain->off) {
+			/* XXXX Cast is safe for now, since win32 has no
+			   mmaped chains.  But later, we need to have this
+			   add more WSAbufs if chain->off is greater than
+			   ULONG_MAX */
+			b->len = (unsigned long)chain->off;
+			at_most -= chain->off;
+		} else {
+			b->len = (unsigned long)at_most;
+			++i;
+			break;
+		}
+	}
+
+	buf_o->n_buffers = i;
+	_evbuffer_incref(buf);
+	if (WSASend(buf_o->fd, buf_o->buffers, i, &bytesSent, 0,
+		&ol->overlapped, NULL)) {
+		int error = WSAGetLastError();
+		if (error != WSA_IO_PENDING) {
+			/* An actual error. */
+			pin_release(buf_o, EVBUFFER_MEM_PINNED_W);
+			evbuffer_unfreeze(buf, 1);
+			evbuffer_free(buf); /* decref */
+			goto done;
+		}
+	}
+
+	buf_o->write_in_progress = 1;
+	r = 0;
+done:
+	EVBUFFER_UNLOCK(buf);
+	return r;
+}
+
+int
+evbuffer_launch_read(struct evbuffer *buf, size_t at_most,
+		struct event_overlapped *ol)
+{
+	struct evbuffer_overlapped *buf_o = upcast_evbuffer(buf);
+	int r = -1, i;
+	int nvecs;
+	int npin=0;
+	struct evbuffer_chain *chain=NULL, **chainp;
+	DWORD bytesRead;
+	DWORD flags = 0;
+	struct evbuffer_iovec vecs[MAX_WSABUFS];
+
+	if (!buf_o)
+		return -1;
+	EVBUFFER_LOCK(buf);
+	EVUTIL_ASSERT(!buf_o->write_in_progress);
+	if (buf->freeze_end || buf_o->read_in_progress)
+		goto done;
+
+	buf_o->first_pinned = NULL;
+	buf_o->n_buffers = 0;
+	memset(buf_o->buffers, 0, sizeof(buf_o->buffers));
+
+	if (_evbuffer_expand_fast(buf, at_most, MAX_WSABUFS) == -1)
+		goto done;
+	evbuffer_freeze(buf, 0);
+
+	nvecs = _evbuffer_read_setup_vecs(buf, at_most,
+	    vecs, MAX_WSABUFS, &chainp, 1);
+	for (i=0;i<nvecs;++i) {
+		WSABUF_FROM_EVBUFFER_IOV(
+			&buf_o->buffers[i],
+			&vecs[i]);
+	}
+
+	buf_o->n_buffers = nvecs;
+	buf_o->first_pinned = chain = *chainp;
+
+	npin=0;
+	for ( ; chain; chain = chain->next) {
+		_evbuffer_chain_pin(chain, EVBUFFER_MEM_PINNED_R);
+		++npin;
+	}
+	EVUTIL_ASSERT(npin == nvecs);
+
+	_evbuffer_incref(buf);
+	if (WSARecv(buf_o->fd, buf_o->buffers, nvecs, &bytesRead, &flags,
+		    &ol->overlapped, NULL)) {
+		int error = WSAGetLastError();
+		if (error != WSA_IO_PENDING) {
+			/* An actual error. */
+			pin_release(buf_o, EVBUFFER_MEM_PINNED_R);
+			evbuffer_unfreeze(buf, 0);
+			evbuffer_free(buf); /* decref */
+			goto done;
+		}
+	}
+
+	buf_o->read_in_progress = 1;
+	r = 0;
+done:
+	EVBUFFER_UNLOCK(buf);
+	return r;
+}
+
+evutil_socket_t
+_evbuffer_overlapped_get_fd(struct evbuffer *buf)
+{
+	struct evbuffer_overlapped *buf_o = upcast_evbuffer(buf);
+	return buf_o ? buf_o->fd : -1;
+}
+
+void
+_evbuffer_overlapped_set_fd(struct evbuffer *buf, evutil_socket_t fd)
+{
+	struct evbuffer_overlapped *buf_o = upcast_evbuffer(buf);
+	EVBUFFER_LOCK(buf);
+	/* XXX is this right?, should it cancel current I/O operations? */
+	if (buf_o)
+		buf_o->fd = fd;
+	EVBUFFER_UNLOCK(buf);
+}