diff --git a/MdePkg/Library/BaseMemoryLibRepStr/BaseMemoryLibRepStr.inf b/MdePkg/Library/BaseMemoryLibRepStr/BaseMemoryLibRepStr.inf
index 44287d05dc..3f923657d9 100644
--- a/MdePkg/Library/BaseMemoryLibRepStr/BaseMemoryLibRepStr.inf
+++ b/MdePkg/Library/BaseMemoryLibRepStr/BaseMemoryLibRepStr.inf
@@ -46,6 +46,7 @@
   MemLibGuid.c
 
 [Sources.Ia32]
+  Ia32/ScanMem64.nasm
   Ia32/ScanMem64.S
   Ia32/ScanMem32.S
   Ia32/ScanMem16.S
@@ -57,6 +58,7 @@
   Ia32/SetMem16.S
   Ia32/SetMem.S
   Ia32/CopyMem.S
+  Ia32/ScanMem64.nasm
   Ia32/ScanMem64.asm
   Ia32/ScanMem32.asm
   Ia32/ScanMem16.asm
diff --git a/MdePkg/Library/BaseMemoryLibRepStr/Ia32/ScanMem64.nasm b/MdePkg/Library/BaseMemoryLibRepStr/Ia32/ScanMem64.nasm
new file mode 100644
index 0000000000..c243557f06
--- /dev/null
+++ b/MdePkg/Library/BaseMemoryLibRepStr/Ia32/ScanMem64.nasm
@@ -0,0 +1,65 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2006 - 2015, 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:
+;
+;   ScanMem64.Asm
+;
+; Abstract:
+;
+;   ScanMem64 function
+;
+; Notes:
+;
+;   The following BaseMemoryLib instances contain the same copy of this file:
+;
+;       BaseMemoryLibRepStr
+;       BaseMemoryLibMmx
+;       BaseMemoryLibSse2
+;       BaseMemoryLibOptDxe
+;       BaseMemoryLibOptPei
+;
+;------------------------------------------------------------------------------
+
+    SECTION .text
+
+;------------------------------------------------------------------------------
+; CONST VOID *
+; EFIAPI
+; InternalMemScanMem64 (
+;   IN      CONST VOID                *Buffer,
+;   IN      UINTN                     Length,
+;   IN      UINT64                    Value
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(InternalMemScanMem64)
+ASM_PFX(InternalMemScanMem64):
+    push    edi
+    mov     ecx, [esp + 12]
+    mov     eax, [esp + 16]
+    mov     edx, [esp + 20]
+    mov     edi, [esp + 8]
+.0:
+    cmp     eax, [edi]
+    lea     edi, [edi + 8]
+    loopne  .0
+    jne     .1
+    cmp     edx, [edi - 4]
+    jecxz   .1
+    jne     .0
+.1:
+    lea     eax, [edi - 8]
+    jz      .2
+    mov     eax, ecx
+.2:
+    pop     edi
+    ret
+