Index: docs/LangRef.rst
===================================================================
--- docs/LangRef.rst
+++ docs/LangRef.rst
@@ -3144,6 +3144,42 @@
 linker, or an option that is reserved by the target specific assembly writer or
 object file emitter. No other aspect of these options is defined by the IR.
 
+C type width Module Flags Metadata
+----------------------------------
+
+The ARM backend emits a section into each generated object file describing the
+options that it was compiled with (in a compiler-independent way) to prevent
+linking incompatible objects, and to allow automatic library selection. Some
+of these options are not visible at the IR level, namely wchar_t width and enum
+width.
+
+To pass this information to the backend, these options are encoded in module
+flags metadata, using the following key-value pairs:
+
+.. list-table::
+   :header-rows: 1
+   :widths: 30 70
+
+   * - Key
+     - Value
+
+   * - short_wchar
+     - * 0 --- sizeof(wchar_t) == 4
+       * 1 --- sizeof(wchar_t) == 2
+
+   * - short_enum
+     - * 0 --- Enums are at least as large as an ``int``.
+       * 1 --- Enums are stored in the smallest integer type which can
+         represent all of its values.
+
+For example, the following metadata section specifies that the module was
+compiled with a ``wchar_t`` width of 4 bytes, and the underlying type of an
+enum is the smallest type which can represent all of its values::
+
+    !llvm.module.flags = !{!0, !1}
+    !0 = metadata !{i32 1, metadata !"short_wchar", i32 1}
+    !1 = metadata !{i32 1, metadata !"short_enum", i32 0}
+
 .. _intrinsicglobalvariables:
 
 Intrinsic Global Variables
Index: include/llvm/Support/ARMBuildAttributes.h
===================================================================
--- include/llvm/Support/ARMBuildAttributes.h
+++ include/llvm/Support/ARMBuildAttributes.h
@@ -159,6 +159,11 @@
   AddressDirect = 1, // Address imported data directly
   AddressGOT = 2, // Address imported data indirectly (via GOT)
 
+  // Tag_ABI_PCS_wchar_t
+  WCharProhibited = 0,  // wchar_t is not used
+  WCharWidth2Bytes = 2, // sizeof(wchar_t) == 2
+  WCharWidth4Bytes = 4, // sizeof(wchar_t) == 4
+
   // Tag_ABI_FP_denormal, (=20), uleb128
   PreserveFPSign = 2, // sign when flushed-to-zero is preserved
 
@@ -166,6 +171,16 @@
   AllowRTABI = 2,  // numbers, infinities, and one quiet NaN (see [RTABI])
   AllowIEE754 = 3, // this code to use all the IEEE 754-defined FP encodings
 
+  // Tag_ABI_enum_size
+  EnumProhibited = 0, // The user prohibited the use of enums when building
+                      // this entity.
+  EnumSmallest = 1,   // Enum is smallest container big enough to hold all
+                      // values.
+  Enum32Bit = 2,      // Enum is at least 32 bits.
+  Enum32BitABI = 3,   // Every enumeration visible across an ABI-complying
+                      // interface contains a value needing 32 bits to encode
+                      // it; other enums can be containerized.
+
   // Tag_ABI_HardFP_use, (=27), uleb128
   HardFPImplied = 0,          // FP use should be implied by Tag_FP_arch
   HardFPSinglePrecision = 1,  // Single-precision only
Index: lib/Target/ARM/ARMAsmPrinter.cpp
===================================================================
--- lib/Target/ARM/ARMAsmPrinter.cpp
+++ lib/Target/ARM/ARMAsmPrinter.cpp
@@ -730,6 +730,30 @@
   if (Subtarget->hasDivideInARMMode() && !Subtarget->hasV8Ops())
       ATS.emitAttribute(ARMBuildAttrs::DIV_use, ARMBuildAttrs::AllowDIVExt);
 
+  if (MMI) {
+    if (const Module *SourceModule = MMI->getModule()) {
+      // ABI_PCS_wchar_t to indicate wchar_t width
+      const ConstantInt *WCharWidthValue =
+          cast_or_null<ConstantInt>(SourceModule->getModuleFlag("short_wchar"));
+      if (WCharWidthValue) {
+        int WCharWidth = WCharWidthValue->getZExtValue()
+                             ? ARMBuildAttrs::WCharWidth2Bytes
+                             : ARMBuildAttrs::WCharWidth4Bytes;
+        ATS.emitAttribute(ARMBuildAttrs::ABI_PCS_wchar_t, WCharWidth);
+      }
+
+      // ABI_enum_size to indicate enum width
+      const ConstantInt *EnumWidthValue =
+          cast_or_null<ConstantInt>(SourceModule->getModuleFlag("short_enum"));
+      if (EnumWidthValue) {
+        int EnumWidth = EnumWidthValue->getZExtValue()
+                            ? ARMBuildAttrs::EnumSmallest
+                            : ARMBuildAttrs::Enum32Bit;
+        ATS.emitAttribute(ARMBuildAttrs::ABI_enum_size, EnumWidth);
+      }
+    }
+  }
+
   if (Subtarget->hasTrustZone() && Subtarget->hasVirtualization())
       ATS.emitAttribute(ARMBuildAttrs::Virtualization_use,
                         ARMBuildAttrs::AllowTZVirtualization);
Index: test/CodeGen/ARM/metadata-default.ll
===================================================================
--- /dev/null
+++ test/CodeGen/ARM/metadata-default.ll
@@ -0,0 +1,17 @@
+; RUN: llc < %s -mtriple=armv7-linux-gnueabi | FileCheck %s
+
+; ModuleID = '-'
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-n32-S64"
+target triple = "armv7--none-eabi"
+
+define i32 @f(i64 %z) {
+	ret i32 0
+}
+
+!llvm.module.flags = !{!0, !1}
+
+!0 = metadata !{i32 1, metadata !"short_wchar", i32 0}
+!1 = metadata !{i32 1, metadata !"short_enum", i32 0}
+
+; CHECK: .eabi_attribute 18, 4   @ Tag_ABI_PCS_wchar_t
+; CHECK: .eabi_attribute 26, 2   @ Tag_ABI_enum_size
Index: test/CodeGen/ARM/metadata-short-enums.ll
===================================================================
--- /dev/null
+++ test/CodeGen/ARM/metadata-short-enums.ll
@@ -0,0 +1,17 @@
+; RUN: llc < %s | FileCheck %s
+
+; ModuleID = '-'
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-n32-S64"
+target triple = "armv7--none-eabi"
+
+define i32 @f(i64 %z) {
+	ret i32 0
+}
+
+!llvm.module.flags = !{!0, !1}
+
+!0 = metadata !{i32 1, metadata !"short_wchar", i32 0}
+!1 = metadata !{i32 1, metadata !"short_enum", i32 1}
+
+; CHECK: .eabi_attribute 18, 4   @ Tag_ABI_PCS_wchar_t
+; CHECK: .eabi_attribute 26, 1   @ Tag_ABI_enum_size
Index: test/CodeGen/ARM/metadata-short-wchar.ll
===================================================================
--- /dev/null
+++ test/CodeGen/ARM/metadata-short-wchar.ll
@@ -0,0 +1,17 @@
+; RUN: llc < %s | FileCheck %s
+
+; ModuleID = '-'
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-n32-S64"
+target triple = "armv7--none-eabi"
+
+define i32 @f(i64 %z) {
+	ret i32 0
+}
+
+!llvm.module.flags = !{!0, !1}
+
+!0 = metadata !{i32 1, metadata !"short_wchar", i32 1}
+!1 = metadata !{i32 1, metadata !"short_enum", i32 0}
+
+; CHECK: .eabi_attribute 18, 2   @ Tag_ABI_PCS_wchar_t
+; CHECK: .eabi_attribute 26, 2   @ Tag_ABI_enum_size