Index: clang/include/clang/Basic/TargetInfo.h
===================================================================
--- clang/include/clang/Basic/TargetInfo.h
+++ clang/include/clang/Basic/TargetInfo.h
@@ -130,7 +130,7 @@
   };
 protected:
   IntType SizeType, IntMaxType, PtrDiffType, IntPtrType, WCharType,
-          WIntType, Char16Type, Char32Type, Int64Type, SigAtomicType,
+          WIntType, Char16Type, Char32Type, Int64Type, Int16Type, SigAtomicType,
           ProcessIDType;
 
   /// Whether Objective-C's built-in boolean type should be signed char.
@@ -351,6 +351,10 @@
   IntType getUInt64Type() const {
     return getCorrespondingUnsignedType(Int64Type);
   }
+  IntType getInt16Type() const { return Int16Type; }
+  IntType getUInt16Type() const {
+    return getCorrespondingUnsignedType(Int16Type);
+  }
   IntType getSigAtomicType() const { return SigAtomicType; }
   IntType getProcessIDType() const { return ProcessIDType; }
 
Index: clang/lib/Basic/TargetInfo.cpp
===================================================================
--- clang/lib/Basic/TargetInfo.cpp
+++ clang/lib/Basic/TargetInfo.cpp
@@ -98,6 +98,7 @@
   Char16Type = UnsignedShort;
   Char32Type = UnsignedInt;
   Int64Type = SignedLongLong;
+  Int16Type = SignedShort;
   SigAtomicType = SignedInt;
   ProcessIDType = SignedInt;
   UseSignedCharForObjCBool = true;
Index: clang/lib/Basic/Targets/AVR.h
===================================================================
--- clang/lib/Basic/Targets/AVR.h
+++ clang/lib/Basic/Targets/AVR.h
@@ -52,6 +52,7 @@
     IntPtrType = SignedInt;
     Char16Type = UnsignedInt;
     WIntType = SignedInt;
+    Int16Type = SignedInt;
     Char32Type = UnsignedLong;
     SigAtomicType = SignedChar;
     resetDataLayout("e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8");
Index: clang/lib/Basic/Targets/AVR.cpp
===================================================================
--- clang/lib/Basic/Targets/AVR.cpp
+++ clang/lib/Basic/Targets/AVR.cpp
@@ -309,8 +309,6 @@
   Builder.defineMacro("__AVR__");
   Builder.defineMacro("__ELF__");
   Builder.defineMacro("__flash", "__attribute__((address_space(1)))");
-  Builder.defineMacro("__UINT16_TYPE__", "unsigned int");
-  Builder.defineMacro("__INT16_TYPE__", "int");
 
   if (!this->CPU.empty()) {
     auto It = llvm::find_if(
Index: clang/lib/Frontend/InitPreprocessor.cpp
===================================================================
--- clang/lib/Frontend/InitPreprocessor.cpp
+++ clang/lib/Frontend/InitPreprocessor.cpp
@@ -216,6 +216,11 @@
   if (TypeWidth == 64)
     Ty = IsSigned ? TI.getInt64Type() : TI.getUInt64Type();
 
+  // Use the target specified int16 type when appropriate. Some MCU targets
+  // (such as AVR) have definition of [u]int16_t to [un]signed int.
+  if (TypeWidth == 16)
+    Ty = IsSigned ? TI.getInt16Type() : TI.getUInt16Type();
+
   const char *Prefix = IsSigned ? "__INT" : "__UINT";
 
   DefineType(Prefix + Twine(TypeWidth) + "_TYPE__", Ty, Builder);