Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -459,6 +459,8 @@
   case llvm::Triple::aarch64_be:
   case llvm::Triple::arm:
   case llvm::Triple::armeb:
+  case llvm::Triple::thumb:
+  case llvm::Triple::thumbeb:
     if (Triple.isOSDarwin() || Triple.isOSWindows())
       return true;
     return false;
Index: test/Lexer/wchar-signedness.c
===================================================================
--- test/Lexer/wchar-signedness.c
+++ test/Lexer/wchar-signedness.c
@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 -fsyntax-only -dM -E %s -triple x86_64-none-linux-gnu | FileCheck %s --check-prefix=CHECK-X86
 // RUN: %clang_cc1 -fsyntax-only -dM -E %s -triple armv7-none-eabi | FileCheck %s --check-prefix=CHECK-ARM
+// RUN: %clang_cc1 -fsyntax-only -dM -E %s -triple thumbv7-none-eabi | FileCheck %s --check-prefix=CHECK-ARM
 
 // CHECK-X86-NOT: #define __WCHAR_UNSIGNED__
 // CHECK-X86: #define __WINT_UNSIGNED__ 1