diff --git a/clang/lib/Headers/cpuid.h b/clang/lib/Headers/cpuid.h
--- a/clang/lib/Headers/cpuid.h
+++ b/clang/lib/Headers/cpuid.h
@@ -235,7 +235,6 @@
 #define bit_WBNOINVD    0x00000200
 
 
-#if __i386__
 #define __cpuid(__leaf, __eax, __ebx, __ecx, __edx) \
     __asm("cpuid" : "=a"(__eax), "=b" (__ebx), "=c"(__ecx), "=d"(__edx) \
                   : "0"(__leaf))
@@ -243,22 +242,6 @@
 #define __cpuid_count(__leaf, __count, __eax, __ebx, __ecx, __edx) \
     __asm("cpuid" : "=a"(__eax), "=b" (__ebx), "=c"(__ecx), "=d"(__edx) \
                   : "0"(__leaf), "2"(__count))
-#else
-/* x86-64 uses %rbx as the base register, so preserve it. */
-#define __cpuid(__leaf, __eax, __ebx, __ecx, __edx) \
-    __asm("  xchgq  %%rbx,%q1\n" \
-          "  cpuid\n" \
-          "  xchgq  %%rbx,%q1" \
-        : "=a"(__eax), "=r" (__ebx), "=c"(__ecx), "=d"(__edx) \
-        : "0"(__leaf))
-
-#define __cpuid_count(__leaf, __count, __eax, __ebx, __ecx, __edx) \
-    __asm("  xchgq  %%rbx,%q1\n" \
-          "  cpuid\n" \
-          "  xchgq  %%rbx,%q1" \
-        : "=a"(__eax), "=r" (__ebx), "=c"(__ecx), "=d"(__edx) \
-        : "0"(__leaf), "2"(__count))
-#endif
 
 static __inline int __get_cpuid_max (unsigned int __leaf, unsigned int *__sig)
 {