diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
index 0969b373e8..c7bba68eed 100644
--- a/OvmfPkg/OvmfPkgIa32.dsc
+++ b/OvmfPkg/OvmfPkgIa32.dsc
@@ -1,7 +1,7 @@
 ## @file
 #  EFI/Framework Open Virtual Machine Firmware (OVMF) platform
 #
-#  Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
+#  Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
 #  (C) Copyright 2016 Hewlett Packard Enterprise Development LP<BR>
 #
 #  This program and the accompanying materials
@@ -64,7 +64,9 @@
   GCC:RELEASE_*_*_CC_FLAGS             = -DMDEPKG_NDEBUG
   INTEL:RELEASE_*_*_CC_FLAGS           = /D MDEPKG_NDEBUG
   MSFT:RELEASE_*_*_CC_FLAGS            = /D MDEPKG_NDEBUG
+!if $(TOOL_CHAIN_TAG) != "XCODE5"
   GCC:*_*_*_CC_FLAGS                   = -mno-mmx -mno-sse
+!endif
 
   #
   # Disable deprecated APIs.
diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index 637fcf89a8..e7c2979f77 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -1,7 +1,7 @@
 ## @file
 #  EFI/Framework Open Virtual Machine Firmware (OVMF) platform
 #
-#  Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
+#  Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
 #  (C) Copyright 2016 Hewlett Packard Enterprise Development LP<BR>
 #
 #  This program and the accompanying materials
@@ -64,7 +64,9 @@
   GCC:RELEASE_*_*_CC_FLAGS             = -DMDEPKG_NDEBUG
   INTEL:RELEASE_*_*_CC_FLAGS           = /D MDEPKG_NDEBUG
   MSFT:RELEASE_*_*_CC_FLAGS            = /D MDEPKG_NDEBUG
+!if $(TOOL_CHAIN_TAG) != "XCODE5"
   GCC:*_*_*_CC_FLAGS                   = -mno-mmx -mno-sse
+!endif
 !ifdef $(SOURCE_DEBUG_ENABLE)
   MSFT:*_*_X64_GENFW_FLAGS  = --keepexceptiontable
   GCC:*_*_X64_GENFW_FLAGS   = --keepexceptiontable
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index ff7466926a..9dfdaa0705 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -1,7 +1,7 @@
 ## @file
 #  EFI/Framework Open Virtual Machine Firmware (OVMF) platform
 #
-#  Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
+#  Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
 #  (C) Copyright 2016 Hewlett Packard Enterprise Development LP<BR>
 #
 #  This program and the accompanying materials
@@ -64,7 +64,9 @@
   GCC:RELEASE_*_*_CC_FLAGS             = -DMDEPKG_NDEBUG
   INTEL:RELEASE_*_*_CC_FLAGS           = /D MDEPKG_NDEBUG
   MSFT:RELEASE_*_*_CC_FLAGS            = /D MDEPKG_NDEBUG
+!if $(TOOL_CHAIN_TAG) != "XCODE5"
   GCC:*_*_*_CC_FLAGS                   = -mno-mmx -mno-sse
+!endif
 !ifdef $(SOURCE_DEBUG_ENABLE)
   MSFT:*_*_X64_GENFW_FLAGS  = --keepexceptiontable
   GCC:*_*_X64_GENFW_FLAGS   = --keepexceptiontable