Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -987,6 +987,7 @@
 def m64 : Flag<["-"], "m64">, Group<m_Group>, Flags<[DriverOption, CoreOption]>;
 def mabi_EQ : Joined<["-"], "mabi=">, Group<m_Group>;
 def march_EQ : Joined<["-"], "march=">, Group<m_Group>;
+def mbig_endian : Flag<["-"], "mbig-endian">, Alias<EB>;
 def mcmodel_EQ : Joined<["-"], "mcmodel=">, Group<m_Group>;
 def mconstant_cfstrings : Flag<["-"], "mconstant-cfstrings">, Group<clang_ignored_m_Group>;
 def mcpu_EQ : Joined<["-"], "mcpu=">, Group<m_Group>;
@@ -1007,6 +1008,7 @@
 def mkernel : Flag<["-"], "mkernel">, Group<m_Group>;
 def mlinker_version_EQ : Joined<["-"], "mlinker-version=">,
   Flags<[DriverOption]>;
+def mlittle_endian : Flag<["-"], "mlittle-endian">, Alias<EL>;
 def mllvm : Separate<["-"], "mllvm">, Flags<[CC1Option]>,
   HelpText<"Additional arguments to forward to LLVM's option processing">;
 def mmacosx_version_min_EQ : Joined<["-"], "mmacosx-version-min=">, Group<m_Group>;
Index: lib/Driver/Driver.cpp
===================================================================
--- lib/Driver/Driver.cpp
+++ lib/Driver/Driver.cpp
@@ -1870,11 +1870,15 @@
         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 +1,44 @@
 // 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
+// RUN: %clang -target aarch64 -EL -### -c %s 2>&1 | FileCheck -check-prefix=GENERIC %s
+// RUN: %clang -target aarch64_be -EL -### -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
+// RUN: %clang -target aarch64 -EL -mcpu=cortex-a53 -### -c %s 2>&1 | FileCheck -check-prefix=CA53 %s
+// RUN: %clang -target aarch64_be -EL -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
+// RUN: %clang -target aarch64 -EL -mcpu=cortex-a57 -### -c %s 2>&1 | FileCheck -check-prefix=CA57 %s
+// RUN: %clang -target aarch64_be -EL -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
+// RUN: %clang -target aarch64 -EB -### -c %s 2>&1 | FileCheck -check-prefix=GENERIC-BE %s
+// RUN: %clang -target aarch64_be -EB -### -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
+// RUN: %clang -target aarch64 -EB -mcpu=cortex-a53 -### -c %s 2>&1 | FileCheck -check-prefix=CA53-BE %s
+// RUN: %clang -target aarch64_be -EB -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
+// RUN: %clang -target aarch64 -EB -mcpu=cortex-a57 -### -c %s 2>&1 | FileCheck -check-prefix=CA57-BE %s
+// RUN: %clang -target aarch64_be -EB -mcpu=cortex-a57 -### -c %s 2>&1 | FileCheck -check-prefix=CA57-BE %s
 // CA57-BE: "-cc1"{{.*}} "-triple" "aarch64_be{{.*}}" "-target-cpu" "cortex-a57"