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
@@ -328,14 +328,4 @@
     return 1;
 }
 
-// If MS extensions are enabled, __cpuidex is defined as a builtin which will
-// conflict with the __cpuidex definition below.
-#ifndef _MSC_EXTENSIONS
-static __inline void __cpuidex (int __cpu_info[4], int __leaf, int __subleaf)
-{
-  __cpuid_count(__leaf, __subleaf, __cpu_info[0], __cpu_info[1], __cpu_info[2],
-                __cpu_info[3]);
-}
-#endif
-
 #endif /* __CPUID_H */
diff --git a/clang/test/Headers/__cpuidex_conflict.c b/clang/test/Headers/__cpuidex_conflict.c
deleted file mode 100644
--- a/clang/test/Headers/__cpuidex_conflict.c
+++ /dev/null
@@ -1,15 +0,0 @@
-// Make sure that __cpuidex in cpuid.h doesn't conflict with the MS
-// compatibility built in by ensuring compilation succeeds:
-// RUN: %clang_cc1 %s -ffreestanding -fms-extensions -fms-compatibility \
-// RUN:  -fms-compatibility-version=19.00 -triple x86_64-pc-windows-msvc -emit-llvm -o -
-
-typedef __SIZE_TYPE__ size_t;
-
-#include <intrin.h>
-#include <cpuid.h>
-
-int cpuid_info[4];
-
-void test_cpuidex(unsigned level, unsigned count) {
-  __cpuidex(cpuid_info, level, count);
-}
diff --git a/clang/test/Headers/cpuid.c b/clang/test/Headers/cpuid.c
--- a/clang/test/Headers/cpuid.c
+++ b/clang/test/Headers/cpuid.c
@@ -6,19 +6,14 @@
 
 // CHECK-64: {{.*}} call { i32, i32, i32, i32 } asm "  xchgq  %rbx,${1:q}\0A cpuid\0A xchgq %rbx,${1:q}", "={ax},=r,={cx},={dx},0,~{dirflag},~{fpsr},~{flags}"(i32 %{{[a-z0-9]+}})
 // CHECK-64: {{.*}} call { i32, i32, i32, i32 } asm "  xchgq  %rbx,${1:q}\0A  cpuid\0A  xchgq  %rbx,${1:q}", "={ax},=r,={cx},={dx},0,2,~{dirflag},~{fpsr},~{flags}"(i32 %{{[a-z0-9]+}}, i32 %{{[a-z0-9]+}})
-// CHECK-64: {{.*}} call { i32, i32, i32, i32 } asm "  xchgq  %rbx,${1:q}\0A  cpuid\0A  xchgq  %rbx,${1:q}", "={ax},=r,={cx},={dx},0,2,~{dirflag},~{fpsr},~{flags}"(i32 %{{[a-z0-9]+}}, i32 %{{[a-z0-9]+}})
 
 // CHECK-32: {{.*}} call { i32, i32, i32, i32 } asm "cpuid", "={ax},={bx},={cx},={dx},0,~{dirflag},~{fpsr},~{flags}"(i32 %{{[a-z0-9]+}})
 // CHECK-32: {{.*}} call { i32, i32, i32, i32 } asm "cpuid", "={ax},={bx},={cx},={dx},0,2,~{dirflag},~{fpsr},~{flags}"(i32 %{{[a-z0-9]+}}, i32 %{{[a-z0-9]+}})
-// CHECK-32: {{.*}} call { i32, i32, i32, i32 } asm "cpuid", "={ax},={bx},={cx},={dx},0,2,~{dirflag},~{fpsr},~{flags}"(i32 %{{[a-z0-9]+}}, i32 %{{[a-z0-9]+}})
 
 unsigned eax0, ebx0, ecx0, edx0;
 unsigned eax1, ebx1, ecx1, edx1;
 
-int cpuid_info[4];
-
 void test_cpuid(unsigned level, unsigned count) {
   __cpuid(level, eax1, ebx1, ecx1, edx1);
   __cpuid_count(level, count, eax0, ebx0, ecx0, edx0);
-  __cpuidex(cpuid_info, level, count);
 }