Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -755,10 +755,9 @@
       break;
     case llvm::Triple::EABIHF:
     case llvm::Triple::EABI:
+    default:
       ABIName = "aapcs";
       break;
-    default:
-      ABIName = "apcs-gnu";
     }
   }
   CmdArgs.push_back("-target-abi");
Index: test/Driver/arm-abi.c
===================================================================
--- /dev/null
+++ test/Driver/arm-abi.c
@@ -0,0 +1,45 @@
+// The default ABI is aapcs
+// RUN: %clang -target arm--- %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS %s
+// RUN: %clang -target armeb--- %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS %s
+// RUN: %clang -target thumb--- %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS %s
+// RUN: %clang -target thumbeb--- %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS %s
+
+// MachO targets default to apcs-gnu, except for m-class processors
+// RUN: %clang -target arm--darwin- -arch armv7s %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-APCS-GNU %s
+// RUN: %clang -target thumb--darwin- -arch armv7s %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-APCS-GNU %s
+// RUN: %clang -target thumb--darwin- -arch armv7m %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS %s
+
+// Windows targets default to AAPCS, regardless of environment
+// RUN: %clang -target arm--windows-gnueabi %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS %s
+
+// Otherwise, ABI is celected based on environment
+// RUN: %clang -target arm---android %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS-LINUX %s
+// RUN: %clang -target arm---gnueabi %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS-LINUX %s
+// RUN: %clang -target arm---gnueabihf %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS-LINUX %s
+// RUN: %clang -target arm---eabi %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS %s
+// RUN: %clang -target arm---eabihf %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS %s
+
+// ABI can be overridden by the -mabi= option
+// RUN: %clang -target arm---eabi -mabi=apcs-gnu %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-APCS-GNU %s
+// RUN: %clang -target arm---gnueabi -mabi=aapcs %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS %s
+// RUN: %clang -target arm---eabi -mabi=aapcs-linux %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS-LINUX %s
+
+// CHECK-APCS-GNU: "-target-abi" "apcs-gnu"
+// CHECK-AAPCS: "-target-abi" "aapcs"
+// CHECK-AAPCS-LINUX: "-target-abi" "aapcs-linux"
Index: test/Preprocessor/init.c
===================================================================
--- test/Preprocessor/init.c
+++ test/Preprocessor/init.c
@@ -1764,12 +1764,13 @@
 // ARM-NETBSD:#define __arm 1
 // ARM-NETBSD:#define __arm__ 1
 
-// RUN: %clang -target arm -arch armv7s -x c -E -dM %s -o - | FileCheck --check-prefix=ARM-DARWIN-NO-EABI %s
-// RUN: %clang -target arm -arch armv6m -x c -E -dM %s -o - | FileCheck --check-prefix=ARM-DARWIN-NO-EABI %s
-// RUN: %clang -target arm -arch armv7m -x c -E -dM %s -o - | FileCheck --check-prefix=ARM-DARWIN-NO-EABI %s
-// RUN: %clang -target arm -arch armv7em -x c -E -dM %s -o - | FileCheck --check-prefix=ARM-DARWIN-NO-EABI %s
+// RUN: %clang -target arm-apple-darwin-eabi -arch armv7s -x c -E -dM %s -o - | FileCheck --check-prefix=ARM-DARWIN-NO-EABI %s
+// RUN: %clang -target arm-apple-darwin-eabi -arch armv6m -x c -E -dM %s -o - | FileCheck --check-prefix=ARM-DARWIN-EABI %s
+// RUN: %clang -target arm-apple-darwin-eabi -arch armv7m -x c -E -dM %s -o - | FileCheck --check-prefix=ARM-DARWIN-EABI %s
+// RUN: %clang -target arm-apple-darwin-eabi -arch armv7em -x c -E -dM %s -o - | FileCheck --check-prefix=ARM-DARWIN-EABI %s
 // RUN: %clang -target thumbv7-apple-darwin-eabi -arch armv7 -x c -E -dM %s -o - | FileCheck --check-prefix=ARM-DARWIN-NO-EABI %s
 // ARM-DARWIN-NO-EABI-NOT: #define __ARM_EABI__ 1
+// ARM-DARWIN-EABI: #define __ARM_EABI__ 1
 
 // Check that -mhwdiv works properly for targets which don't have the hwdiv feature enabled by default.