diff --git a/MdePkg/Library/BaseMemoryLibRepStr/BaseMemoryLibRepStr.inf b/MdePkg/Library/BaseMemoryLibRepStr/BaseMemoryLibRepStr.inf
index a0ecafadba..e89d047235 100644
--- a/MdePkg/Library/BaseMemoryLibRepStr/BaseMemoryLibRepStr.inf
+++ b/MdePkg/Library/BaseMemoryLibRepStr/BaseMemoryLibRepStr.inf
@@ -110,6 +110,7 @@
   X64/SetMem32.S
   X64/SetMem16.nasm
   X64/SetMem16.S
+  X64/SetMem.nasm
   X64/SetMem.S
   X64/CopyMem.S
   X64/ScanMem64.nasm
@@ -130,6 +131,7 @@
   X64/SetMem32.asm
   X64/SetMem16.nasm
   X64/SetMem16.asm
+  X64/SetMem.nasm
   X64/SetMem.asm
   X64/CopyMem.asm
 
diff --git a/MdePkg/Library/BaseMemoryLibRepStr/X64/SetMem.nasm b/MdePkg/Library/BaseMemoryLibRepStr/X64/SetMem.nasm
new file mode 100644
index 0000000000..79b2d5455b
--- /dev/null
+++ b/MdePkg/Library/BaseMemoryLibRepStr/X64/SetMem.nasm
@@ -0,0 +1,46 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
+; This program and the accompanying materials
+; are licensed and made available under the terms and conditions of the BSD License
+; which accompanies this distribution.  The full text of the license may be found at
+; http://opensource.org/licenses/bsd-license.php.
+;
+; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+;
+; Module Name:
+;
+;   SetMem.Asm
+;
+; Abstract:
+;
+;   SetMem function
+;
+; Notes:
+;
+;------------------------------------------------------------------------------
+
+    DEFAULT REL
+    SECTION .text
+
+;------------------------------------------------------------------------------
+;  VOID *
+;  EFIAPI
+;  InternalMemSetMem (
+;    IN VOID   *Buffer,
+;    IN UINTN  Count,
+;    IN UINT8  Value
+;    )
+;------------------------------------------------------------------------------
+global ASM_PFX(InternalMemSetMem)
+ASM_PFX(InternalMemSetMem):
+    push    rdi
+    mov     rax, r8    ; rax = Value
+    mov     rdi, rcx   ; rdi = Buffer
+    xchg    rcx, rdx   ; rcx = Count, rdx = Buffer
+    rep     stosb
+    mov     rax, rdx   ; rax = Buffer
+    pop     rdi
+    ret
+