diff --git a/test/register_state_check.h b/test/register_state_check.h
index b1cb98335..a779e5c06 100644
--- a/test/register_state_check.h
+++ b/test/register_state_check.h
@@ -140,7 +140,7 @@ class RegisterStateCheck {};
 
 #endif  // _WIN64
 
-#if ARCH_X86
+#if ARCH_X86 || ARCH_X86_64
 #if defined(__GNUC__)
 
 namespace libvpx_test {
@@ -178,7 +178,7 @@ class RegisterStateCheckMMX {
 }  // namespace libvpx_test
 
 #endif  // __GNUC__
-#endif  // ARCH_X86
+#endif  // ARCH_X86 || ARCH_X86_64
 
 #ifndef API_REGISTER_STATE_CHECK
 #define API_REGISTER_STATE_CHECK ASM_REGISTER_STATE_CHECK
diff --git a/vpx_ports/emms_mmx.asm b/vpx_ports/emms_mmx.asm
new file mode 100644
index 000000000..9f33590a2
--- /dev/null
+++ b/vpx_ports/emms_mmx.asm
@@ -0,0 +1,18 @@
+;
+;  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
+;
+;  Use of this source code is governed by a BSD-style license
+;  that can be found in the LICENSE file in the root of the source
+;  tree. An additional intellectual property rights grant can be found
+;  in the file PATENTS.  All contributing project authors may
+;  be found in the AUTHORS file in the root of the source tree.
+;
+
+
+%include "vpx_ports/x86_abi_support.asm"
+
+section .text
+global sym(vpx_clear_system_state) PRIVATE
+sym(vpx_clear_system_state):
+    emms
+    ret
diff --git a/vpx_ports/system_state.h b/vpx_ports/system_state.h
index 0a19c3cfc..72993782a 100644
--- a/vpx_ports/system_state.h
+++ b/vpx_ports/system_state.h
@@ -17,11 +17,11 @@
 extern "C" {
 #endif
 
-#if ARCH_X86 && HAVE_MMX
+#if (ARCH_X86 || ARCH_X86_64) && HAVE_MMX
 extern void vpx_clear_system_state();
 #else
 #define vpx_clear_system_state()
-#endif  // ARCH_X86 && HAVE_MMX
+#endif  // (ARCH_X86 || ARCH_X86_64) && HAVE_MMX
 
 #ifdef __cplusplus
 }  // extern "C"
diff --git a/vpx_ports/vpx_ports.mk b/vpx_ports/vpx_ports.mk
index 9299fa0ca..aa9faf15e 100644
--- a/vpx_ports/vpx_ports.mk
+++ b/vpx_ports/vpx_ports.mk
@@ -20,6 +20,10 @@ PORTS_SRCS-yes += vpx_timer.h
 ifeq ($(ARCH_X86),yes)
 PORTS_SRCS-$(HAVE_MMX) += emms_mmx.c
 endif
+ifeq ($(ARCH_X86_64),yes)
+# Visual Studio x64 does not support the _mm_empty() intrinsic.
+PORTS_SRCS-$(HAVE_MMX) += emms_mmx.asm
+endif
 
 ifeq ($(ARCH_X86_64),yes)
 PORTS_SRCS-$(CONFIG_MSVS) += float_control_word.asm