Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -979,8 +979,10 @@
 def l : JoinedOrSeparate<["-"], "l">, Flags<[LinkerInput, RenderJoined]>;
 def lazy__framework : Separate<["-"], "lazy_framework">, Flags<[LinkerInput]>;
 def lazy__library : Separate<["-"], "lazy_library">, Flags<[LinkerInput]>;
-def EL : Flag<["-"], "EL">, Flags<[DriverOption]>;
-def EB : Flag<["-"], "EB">, Flags<[DriverOption]>;
+def mlittle_endian : Flag<["-"], "mlittle-endian">, Flags<[DriverOption]>;
+def EL : Flag<["-"], "EL">, Alias<mlittle_endian>;
+def mbig_endian : Flag<["-"], "mbig-endian">, Flags<[DriverOption]>;
+def EB : Flag<["-"], "EB">, Alias<mbig_endian>;
 def m16 : Flag<["-"], "m16">, Group<m_Group>, Flags<[DriverOption, CoreOption]>;
 def m32 : Flag<["-"], "m32">, Group<m_Group>, Flags<[DriverOption, CoreOption]>;
 def mqdsp6_compat : Flag<["-"], "mqdsp6-compat">, Group<m_Group>, Flags<[DriverOption,CC1Option]>,
Index: lib/Driver/Driver.cpp
===================================================================
--- lib/Driver/Driver.cpp
+++ lib/Driver/Driver.cpp
@@ -1862,18 +1862,24 @@
     }
   }
 
-  // Handle pseudo-target flags '-EL' and '-EB'.
-  if (Arg *A = Args.getLastArg(options::OPT_EL, options::OPT_EB)) {
-    if (A->getOption().matches(options::OPT_EL)) {
+  // Handle pseudo-target flags '-mlittle-endian'/'-EL' and
+  // '-mbig-endian'/'-EB'.
+  if (Arg *A = Args.getLastArg(options::OPT_mlittle_endian,
+                               options::OPT_mbig_endian)) {
+    if (A->getOption().matches(options::OPT_mlittle_endian)) {
       if (Target.getArch() == llvm::Triple::mips)
         Target.setArch(llvm::Triple::mipsel);
       else if (Target.getArch() == llvm::Triple::mips64)
         Target.setArch(llvm::Triple::mips64el);
+      else if (Target.getArch() == llvm::Triple::aarch64_be)
+        Target.setArch(llvm::Triple::aarch64);
     } else {
       if (Target.getArch() == llvm::Triple::mipsel)
         Target.setArch(llvm::Triple::mips);
       else if (Target.getArch() == llvm::Triple::mips64el)
         Target.setArch(llvm::Triple::mips64);
+      else if (Target.getArch() == llvm::Triple::aarch64)
+        Target.setArch(llvm::Triple::aarch64_be);
     }
   }
 
Index: test/Driver/aarch64-cpus.c
===================================================================
--- test/Driver/aarch64-cpus.c
+++ test/Driver/aarch64-cpus.c
@@ -1,20 +1,32 @@
 // Check target CPUs are correctly passed.
 
 // RUN: %clang -target aarch64 -### -c %s 2>&1 | FileCheck -check-prefix=GENERIC %s
+// RUN: %clang -target aarch64 -mlittle-endian -### -c %s 2>&1 | FileCheck -check-prefix=GENERIC %s
+// RUN: %clang -target aarch64_be -mlittle-endian -### -c %s 2>&1 | FileCheck -check-prefix=GENERIC %s
 // GENERIC: "-cc1"{{.*}} "-triple" "aarch64{{.*}}" "-target-cpu" "generic"
 
 // RUN: %clang -target aarch64 -mcpu=cortex-a53 -### -c %s 2>&1 | FileCheck -check-prefix=CA53 %s
+// RUN: %clang -target aarch64 -mlittle-endian -mcpu=cortex-a53 -### -c %s 2>&1 | FileCheck -check-prefix=CA53 %s
+// RUN: %clang -target aarch64_be -mlittle-endian -mcpu=cortex-a53 -### -c %s 2>&1 | FileCheck -check-prefix=CA53 %s
 // CA53: "-cc1"{{.*}} "-triple" "aarch64{{.*}}" "-target-cpu" "cortex-a53"
 
 // RUN: %clang -target aarch64 -mcpu=cortex-a57 -### -c %s 2>&1 | FileCheck -check-prefix=CA57 %s
+// RUN: %clang -target aarch64 -mlittle-endian -mcpu=cortex-a57 -### -c %s 2>&1 | FileCheck -check-prefix=CA57 %s
+// RUN: %clang -target aarch64_be -mlittle-endian -mcpu=cortex-a57 -### -c %s 2>&1 | FileCheck -check-prefix=CA57 %s
 // CA57: "-cc1"{{.*}} "-triple" "aarch64{{.*}}" "-target-cpu" "cortex-a57"
 
 // RUN: %clang -target aarch64_be -### -c %s 2>&1 | FileCheck -check-prefix=GENERIC-BE %s
+// RUN: %clang -target aarch64 -mbig-endian -### -c %s 2>&1 | FileCheck -check-prefix=GENERIC-BE %s
+// RUN: %clang -target aarch64_be -mbig-endian -### -c %s 2>&1 | FileCheck -check-prefix=GENERIC-BE %s
 // GENERIC-BE: "-cc1"{{.*}} "-triple" "aarch64_be{{.*}}" "-target-cpu" "generic"
 
 // RUN: %clang -target aarch64_be -mcpu=cortex-a53 -### -c %s 2>&1 | FileCheck -check-prefix=CA53-BE %s
+// RUN: %clang -target aarch64 -mbig-endian -mcpu=cortex-a53 -### -c %s 2>&1 | FileCheck -check-prefix=CA53-BE %s
+// RUN: %clang -target aarch64_be -mbig-endian -mcpu=cortex-a53 -### -c %s 2>&1 | FileCheck -check-prefix=CA53-BE %s
 // CA53-BE: "-cc1"{{.*}} "-triple" "aarch64_be{{.*}}" "-target-cpu" "cortex-a53"
 
 // RUN: %clang -target aarch64_be -mcpu=cortex-a57 -### -c %s 2>&1 | FileCheck -check-prefix=CA57-BE %s
+// RUN: %clang -target aarch64 -mbig-endian -mcpu=cortex-a57 -### -c %s 2>&1 | FileCheck -check-prefix=CA57-BE %s
+// RUN: %clang -target aarch64_be -mbig-endian -mcpu=cortex-a57 -### -c %s 2>&1 | FileCheck -check-prefix=CA57-BE %s
 // CA57-BE: "-cc1"{{.*}} "-triple" "aarch64_be{{.*}}" "-target-cpu" "cortex-a57"