diff --git a/qga/Makefile.objs b/qga/Makefile.objs
index 4891732..ae1c28b 100644
--- a/qga/Makefile.objs
+++ b/qga/Makefile.objs
@@ -1,6 +1,7 @@
 qga-obj-y = commands.o guest-agent-command-state.o main.o
 qga-obj-$(CONFIG_POSIX) += commands-posix.o channel-posix.o
 qga-obj-$(CONFIG_WIN32) += commands-win32.o channel-win32.o service-win32.o
+qga-obj-$(CONFIG_WIN32) += vss-win32.o
 qga-obj-y += qapi-generated/qga-qapi-types.o qapi-generated/qga-qapi-visit.o
 qga-obj-y += qapi-generated/qga-qmp-marshal.o
 
diff --git a/qga/commands-win32.c b/qga/commands-win32.c
index 24e4ad0..7a37f5c 100644
--- a/qga/commands-win32.c
+++ b/qga/commands-win32.c
@@ -15,6 +15,7 @@
 #include <wtypes.h>
 #include <powrprof.h>
 #include "qga/guest-agent-core.h"
+#include "qga/vss-win32.h"
 #include "qga-qmp-commands.h"
 #include "qapi/qmp/qerror.h"
 
@@ -156,27 +157,89 @@ void qmp_guest_file_flush(int64_t handle, Error **err)
  */
 GuestFsfreezeStatus qmp_guest_fsfreeze_status(Error **err)
 {
-    error_set(err, QERR_UNSUPPORTED);
-    return 0;
+    if (!vss_initialized()) {
+        error_set(err, QERR_UNSUPPORTED);
+        return 0;
+    }
+
+    if (ga_is_frozen(ga_state)) {
+        return GUEST_FSFREEZE_STATUS_FROZEN;
+    }
+
+    return GUEST_FSFREEZE_STATUS_THAWED;
 }
 
 /*
- * Walk list of mounted file systems in the guest, and freeze the ones which
- * are real local file systems.
+ * Freeze local file systems using Volume Shadow-copy Service.
+ * The frozen state is limited for up to 10 seconds by VSS.
  */
 int64_t qmp_guest_fsfreeze_freeze(Error **err)
 {
-    error_set(err, QERR_UNSUPPORTED);
+    int i;
+    Error *local_err = NULL;
+
+    if (!vss_initialized()) {
+        error_set(err, QERR_UNSUPPORTED);
+        return 0;
+    }
+
+    slog("guest-fsfreeze called");
+
+    /* cannot risk guest agent blocking itself on a write in this state */
+    ga_set_frozen(ga_state);
+
+    qga_vss_fsfreeze(&i, err, true);
+    if (error_is_set(err)) {
+        goto error;
+    }
+
+    return i;
+
+error:
+    qmp_guest_fsfreeze_thaw(&local_err);
+    if (error_is_set(&local_err)) {
+        g_debug("cleanup thaw: %s", error_get_pretty(local_err));
+        error_free(local_err);
+    }
     return 0;
 }
 
 /*
- * Walk list of frozen file systems in the guest, and thaw them.
+ * Thaw local file systems using Volume Shadow-copy Service.
  */
 int64_t qmp_guest_fsfreeze_thaw(Error **err)
 {
-    error_set(err, QERR_UNSUPPORTED);
-    return 0;
+    int i;
+
+    if (!vss_initialized()) {
+        error_set(err, QERR_UNSUPPORTED);
+        return 0;
+    }
+
+    qga_vss_fsfreeze(&i, err, false);
+
+    ga_unset_frozen(ga_state);
+    return i;
+}
+
+static void guest_fsfreeze_cleanup(void)
+{
+    Error *err = NULL;
+
+    if (!vss_initialized()) {
+        return;
+    }
+
+    if (ga_is_frozen(ga_state) == GUEST_FSFREEZE_STATUS_FROZEN) {
+        qmp_guest_fsfreeze_thaw(&err);
+        if (err) {
+            slog("failed to clean up frozen filesystems: %s",
+                 error_get_pretty(err));
+            error_free(err);
+        }
+    }
+
+    vss_deinit(true);
 }
 
 /*
@@ -354,4 +417,7 @@ int64_t qmp_guest_set_vcpus(GuestLogicalProcessorList *vcpus, Error **errp)
 /* register init/cleanup routines for stateful command groups */
 void ga_command_state_init(GAState *s, GACommandState *cs)
 {
+    if (vss_init(true)) {
+        ga_command_state_add(cs, NULL, guest_fsfreeze_cleanup);
+    }
 }
diff --git a/qga/vss-win32.c b/qga/vss-win32.c
new file mode 100644
index 0000000..27d5b14
--- /dev/null
+++ b/qga/vss-win32.c
@@ -0,0 +1,129 @@
+/*
+ * QEMU Guest Agent VSS utility functions
+ *
+ * Copyright Hitachi Data Systems Corp. 2013
+ *
+ * Authors:
+ *  Tomoki Sekiyama   <tomoki.sekiyama@hds.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include <stdio.h>
+#include <windows.h>
+#include "qga/guest-agent-core.h"
+#include "qga/vss-win32.h"
+#include "qga/vss-win32/requester.h"
+
+#define QGA_VSS_DLL "qga-vss.dll"
+
+static HMODULE provider_lib;
+
+/* Call a function in qga-vss.dll with the specified name */
+static HRESULT call_vss_provider_func(const char *func_name)
+{
+    FARPROC WINAPI func;
+
+    g_assert(provider_lib);
+
+    func = GetProcAddress(provider_lib, func_name);
+    if (!func) {
+        char *msg;
+        FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
+                      FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
+                      MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+                      (char *)&msg, 0, NULL);
+        fprintf(stderr, "failed to load %s from %s: %s",
+                func_name, QGA_VSS_DLL, msg);
+        LocalFree(msg);
+        return E_FAIL;
+    }
+
+    return func();
+}
+
+/* Check whether this OS version supports VSS providers */
+static bool vss_check_os_version(void)
+{
+    OSVERSIONINFO OSver;
+
+    OSver.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
+    GetVersionEx(&OSver);
+    if ((OSver.dwMajorVersion == 5 && OSver.dwMinorVersion >= 2) ||
+       OSver.dwMajorVersion > 5) {
+        return true;
+    }
+    return false;
+}
+
+/* Load qga-vss.dll */
+bool vss_init(bool init_requester)
+{
+    if (!vss_check_os_version()) {
+        /* Do nothing if OS doesn't support providers. */
+        fprintf(stderr, "VSS provider is not supported in this OS version: "
+                "fsfreeze is disabled.\n");
+        return false;
+    }
+
+    provider_lib = LoadLibraryA(QGA_VSS_DLL);
+    if (!provider_lib) {
+        char *msg;
+        FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
+                      FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
+                      MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+                      (char *)&msg, 0, NULL);
+        fprintf(stderr, "failed to load %s: %sfsfreeze is disabled\n",
+                QGA_VSS_DLL, msg);
+        LocalFree(msg);
+        return false;
+    }
+
+    if (init_requester) {
+        HRESULT hr = call_vss_provider_func("requester_init");
+        if (FAILED(hr)) {
+            fprintf(stderr, "fsfreeze is disabled.\n");
+            vss_deinit(false);
+            return false;
+        }
+    }
+
+    return true;
+}
+
+/* Unload qga-provider.dll */
+void vss_deinit(bool deinit_requester)
+{
+    if (deinit_requester) {
+        call_vss_provider_func("requester_deinit");
+    }
+    FreeLibrary(provider_lib);
+    provider_lib = NULL;
+}
+
+bool vss_initialized(void)
+{
+    return !!provider_lib;
+}
+
+/* Call VSS requester and freeze/thaw filesystems and applications */
+void qga_vss_fsfreeze(int *nr_volume, Error **err, bool freeze)
+{
+    const char *func_name = freeze ? "requester_freeze" : "requester_thaw";
+    QGAVSSReuqesterFunc func;
+    ErrorSet errset = {
+        .error_set = (ErrorSetFunc)error_set_win32,
+        .errp = (void **)err,
+        .err_class = ERROR_CLASS_GENERIC_ERROR
+    };
+
+    func = (QGAVSSReuqesterFunc)GetProcAddress(provider_lib, func_name);
+    if (!func) {
+        error_setg_win32(err, GetLastError(), "failed to load %s from %s",
+                         func_name, QGA_VSS_DLL);
+        return;
+    }
+
+    func(nr_volume, &errset);
+}
diff --git a/qga/vss-win32.h b/qga/vss-win32.h
new file mode 100644
index 0000000..eac669c
--- /dev/null
+++ b/qga/vss-win32.h
@@ -0,0 +1,24 @@
+/*
+ * QEMU Guest Agent VSS utility declarations
+ *
+ * Copyright Hitachi Data Systems Corp. 2013
+ *
+ * Authors:
+ *  Tomoki Sekiyama   <tomoki.sekiyama@hds.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef VSS_WIN32_H
+#define VSS_WIN32_H
+
+#include "qapi/error.h"
+
+bool vss_init(bool init_requester);
+void vss_deinit(bool deinit_requester);
+bool vss_initialized(void);
+
+void qga_vss_fsfreeze(int *nr_volume, Error **err, bool freeze);
+
+#endif
