Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -1075,11 +1075,11 @@
 def mno_sha : Flag<["-"], "mno-sha">, Group<m_x86_Features_Group>;
 
 def munaligned_access : Flag<["-"], "munaligned-access">, Group<m_arm_Features_Group>,
-  HelpText<"Allow memory accesses to be unaligned (ARM only)">;
+  HelpText<"Allow memory accesses to be unaligned (AArch32/AArch64 only)">;
 def mno_unaligned_access : Flag<["-"], "mno-unaligned-access">, Group<m_arm_Features_Group>,
-  HelpText<"Force all memory accesses to be aligned (ARM only)">;
+  HelpText<"Force all memory accesses to be aligned (AArch32/AArch64 only)">;
 def mstrict_align : Flag<["-"], "mstrict-align">, Alias<mno_unaligned_access>, Flags<[CC1Option,HelpHidden]>,
-  HelpText<"Force all memory accesses to be aligned (ARM only, same as mno-unaligned-access)">;
+  HelpText<"Force all memory accesses to be aligned (AArch64 only, same as mno-unaligned-access)">;
 def mno_thumb : Flag<["-"], "mno-thumb">, Group<m_arm_Features_Group>;
 def mrestrict_it: Flag<["-"], "mrestrict-it">, Group<m_arm_Features_Group>,
   HelpText<"Disallow generation of deprecated IT blocks for ARMv8. It is on by default for ARMv8 Thumb mode.">;
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -3395,10 +3395,18 @@
                                  options::OPT_munaligned_access)) {
       if (A->getOption().matches(options::OPT_mno_unaligned_access)) {
         CmdArgs.push_back("-backend-option");
-        CmdArgs.push_back("-arm-strict-align");
+        if (getToolChain().getTriple().getArch() == llvm::Triple::arm64 ||
+            getToolChain().getTriple().getArch() == llvm::Triple::arm64_be)
+          CmdArgs.push_back("-arm64-strict-align");
+        else
+          CmdArgs.push_back("-arm-strict-align");
       } else {
         CmdArgs.push_back("-backend-option");
-        CmdArgs.push_back("-arm-no-strict-align");
+        if (getToolChain().getTriple().getArch() == llvm::Triple::arm64 ||
+            getToolChain().getTriple().getArch() == llvm::Triple::arm64_be)
+          CmdArgs.push_back("-arm64-no-strict-align");
+        else
+          CmdArgs.push_back("-arm-no-strict-align");
       }
     }
   }
Index: test/Driver/arm-alignment.c
===================================================================
--- test/Driver/arm-alignment.c
+++ test/Driver/arm-alignment.c
@@ -1,25 +1,48 @@
 // RUN: %clang -target arm-none-gnueabi -munaligned-access -### %s 2> %t
-// RUN: FileCheck --check-prefix=CHECK-UNALIGNED < %t %s
+// RUN: FileCheck --check-prefix=CHECK-UNALIGNED-ARM < %t %s
 
 // RUN: %clang -target arm-none-gnueabi -mstrict-align -munaligned-access -### %s 2> %t
-// RUN: FileCheck --check-prefix=CHECK-UNALIGNED < %t %s
+// RUN: FileCheck --check-prefix=CHECK-UNALIGNED-ARM < %t %s
 
 // RUN: %clang -target arm-none-gnueabi -mno-unaligned-access -munaligned-access -### %s 2> %t
-// RUN: FileCheck --check-prefix=CHECK-UNALIGNED < %t %s
+// RUN: FileCheck --check-prefix=CHECK-UNALIGNED-ARM < %t %s
 
-// CHECK-UNALIGNED: "-backend-option" "-arm-no-strict-align"
+// RUN: %clang -target arm64-none-gnueabi -munaligned-access -### %s 2> %t
+// RUN: FileCheck --check-prefix=CHECK-UNALIGNED-ARM64 < %t %s
+
+// RUN: %clang -target arm64-none-gnueabi -mstrict-align -munaligned-access -### %s 2> %t
+// RUN: FileCheck --check-prefix=CHECK-UNALIGNED-ARM64 < %t %s
+
+// RUN: %clang -target arm64-none-gnueabi -mno-unaligned-access -munaligned-access -### %s 2> %t
+// RUN: FileCheck --check-prefix=CHECK-UNALIGNED-ARM64 < %t %s
+
+// CHECK-UNALIGNED-ARM: "-backend-option" "-arm-no-strict-align"
+// CHECK-UNALIGNED-ARM64: "-backend-option" "-arm64-no-strict-align"
 
 
 // RUN: %clang -target arm-none-gnueabi -mno-unaligned-access -### %s 2> %t
-// RUN: FileCheck --check-prefix=CHECK-ALIGNED < %t %s
+// RUN: FileCheck --check-prefix=CHECK-ALIGNED-ARM < %t %s
 
 // RUN: %clang -target arm-none-gnueabi -mstrict-align -### %s 2> %t
-// RUN: FileCheck --check-prefix=CHECK-ALIGNED < %t %s
+// RUN: FileCheck --check-prefix=CHECK-ALIGNED-ARM < %t %s
 
 // RUN: %clang -target arm-none-gnueabi -munaligned-access -mno-unaligned-access -### %s 2> %t
-// RUN: FileCheck --check-prefix=CHECK-ALIGNED < %t %s
+// RUN: FileCheck --check-prefix=CHECK-ALIGNED-ARM < %t %s
 
 // RUN: %clang -target arm-none-gnueabi -munaligned-access -mstrict-align -### %s 2> %t
-// RUN: FileCheck --check-prefix=CHECK-ALIGNED < %t %s
+// RUN: FileCheck --check-prefix=CHECK-ALIGNED-ARM < %t %s
+
+// RUN: %clang -target arm64-none-gnueabi -mno-unaligned-access -### %s 2> %t
+// RUN: FileCheck --check-prefix=CHECK-ALIGNED-ARM64 < %t %s
+
+// RUN: %clang -target arm64-none-gnueabi -mstrict-align -### %s 2> %t
+// RUN: FileCheck --check-prefix=CHECK-ALIGNED-ARM64 < %t %s
+
+// RUN: %clang -target arm64-none-gnueabi -munaligned-access -mno-unaligned-access -### %s 2> %t
+// RUN: FileCheck --check-prefix=CHECK-ALIGNED-ARM64 < %t %s
+
+// RUN: %clang -target arm64-none-gnueabi -munaligned-access -mstrict-align -### %s 2> %t
+// RUN: FileCheck --check-prefix=CHECK-ALIGNED-ARM64 < %t %s
 
-// CHECK-ALIGNED: "-backend-option" "-arm-strict-align"
+// CHECK-ALIGNED-ARM: "-backend-option" "-arm-strict-align"
+// CHECK-ALIGNED-ARM64: "-backend-option" "-arm64-strict-align"