arch/x86/include/asm/string_64.h | 22 ++++++++++++++++++++++
 include/linux/fortify-string.h   |  1 +
 2 files changed, 23 insertions(+)

diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
index 857d364b9888..c623f416789a 100644
--- a/arch/x86/include/asm/string_64.h
+++ b/arch/x86/include/asm/string_64.h
@@ -4,6 +4,10 @@
 
 #ifdef __KERNEL__
 #include <linux/jump_label.h>
+#include <linux/compiler.h>
+#include <linux/const.h>
+#include <asm/alternative.h>
+#include <asm/cpufeatures.h>
 
 /* Written 2002 by Andi Kleen */
 
@@ -18,6 +22,24 @@
 extern void *memcpy(void *to, const void *from, size_t len);
 extern void *__memcpy(void *to, const void *from, size_t len);
 
+extern __always_inline void *__rep_movs_memcpy(void *to, const void *from, size_t len)
+{
+	asm volatile(ALTERNATIVE(
+		"rep movsb",
+		"call rep_movs_alternative",
+		ALT_NOT(X86_FEATURE_FSRM))
+	:"+c" (len), "+D" (to), "+S" (from), ASM_CALL_CONSTRAINT
+	: : "memory", "rax");
+	return to;
+}
+
+#define __builtin_memcpy(to, from, len) \
+	__builtin_choose_expr(__is_constexpr(len), \
+		__builtin_memcpy(to, from, len), \
+		__rep_movs_memcpy(to, from, len))
+
+#define memcpy __builtin_memcpy
+
 #define __HAVE_ARCH_MEMSET
 void *memset(void *s, int c, size_t n);
 void *__memset(void *s, int c, size_t n);
diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
index da51a83b2829..cb778f68f537 100644
--- a/include/linux/fortify-string.h
+++ b/include/linux/fortify-string.h
@@ -690,6 +690,7 @@ __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size,
  * __struct_size() vs __member_size() must be captured here to avoid
  * evaluating argument side-effects further into the macro layers.
  */
+#undef memcpy
 #define memcpy(p, q, s)  __fortify_memcpy_chk(p, q, s,			\
 		__struct_size(p), __struct_size(q),			\
 		__member_size(p), __member_size(q),			\