Index: lib/Basic/Targets.cpp
===================================================================
--- lib/Basic/Targets.cpp
+++ lib/Basic/Targets.cpp
@@ -4817,6 +4817,10 @@
     // Target identification.
     Builder.defineMacro("__arm");
     Builder.defineMacro("__arm__");
+    // For bare-metal none-eabi.
+    if (getTriple().getOS() == llvm::Triple::UnknownOS &&
+        getTriple().getEnvironment() == llvm::Triple::EABI)
+      Builder.defineMacro("__ELF__");
 
     // Target properties.
     Builder.defineMacro("__REGISTER_PREFIX__", "");
Index: test/Preprocessor/init.c
===================================================================
--- test/Preprocessor/init.c
+++ test/Preprocessor/init.c
@@ -2162,6 +2162,9 @@
 // ARM-NETBSD:#define __arm 1
 // ARM-NETBSD:#define __arm__ 1
 
+// RUN: %clang_cc1 -E -dM -ffreestanding -triple=arm-none-eabi < /dev/null | FileCheck -match-full-lines -check-prefix ARM-NONE-EABI %s
+// ARM-NONE-EABI: #define __ELF__ 1
+
 // RUN: %clang -target arm-apple-darwin-eabi -arch armv7s -x c -E -dM %s -o - | FileCheck -match-full-lines --check-prefix=ARM-DARWIN-NO-EABI %s
 // RUN: %clang -target arm-apple-darwin-eabi -arch armv6m -x c -E -dM %s -o - | FileCheck -match-full-lines --check-prefix=ARM-DARWIN-EABI %s
 // RUN: %clang -target arm-apple-darwin-eabi -arch armv7m -x c -E -dM %s -o - | FileCheck -match-full-lines --check-prefix=ARM-DARWIN-EABI %s