Index: include/clang-c/Index.h
===================================================================
--- include/clang-c/Index.h
+++ include/clang-c/Index.h
@@ -3182,8 +3182,14 @@
   CXType_Float128 = 30,
   CXType_Half = 31,
   CXType_Float16 = 32,
+  CXType_ShortAccum = 33,
+  CXType_Accum = 34,
+  CXType_LongAccum = 35,
+  CXType_UShortAccum = 36,
+  CXType_UAccum = 37,
+  CXType_ULongAccum = 38,
   CXType_FirstBuiltin = CXType_Void,
-  CXType_LastBuiltin  = CXType_Float16,
+  CXType_LastBuiltin = CXType_ULongAccum,
 
   CXType_Complex = 100,
   CXType_Pointer = 101,
Index: include/clang/AST/ASTContext.h
===================================================================
--- include/clang/AST/ASTContext.h
+++ include/clang/AST/ASTContext.h
@@ -1007,6 +1007,9 @@
   CanQualType UnsignedCharTy, UnsignedShortTy, UnsignedIntTy, UnsignedLongTy;
   CanQualType UnsignedLongLongTy, UnsignedInt128Ty;
   CanQualType FloatTy, DoubleTy, LongDoubleTy, Float128Ty;
+  CanQualType ShortAccumTy, AccumTy,
+      LongAccumTy;  // ISO/IEC JTC1 SC22 WG14 N1169 Extension
+  CanQualType UnsignedShortAccumTy, UnsignedAccumTy, UnsignedLongAccumTy;
   CanQualType HalfTy; // [OpenCL 6.1.1.1], ARM NEON
   CanQualType Float16Ty; // C11 extension ISO/IEC TS 18661-3
   CanQualType FloatComplexTy, DoubleComplexTy, LongDoubleComplexTy;
Index: include/clang/AST/BuiltinTypes.def
===================================================================
--- include/clang/AST/BuiltinTypes.def
+++ include/clang/AST/BuiltinTypes.def
@@ -122,6 +122,26 @@
 // '__int128_t'
 SIGNED_TYPE(Int128, Int128Ty)
 
+//===- Fixed point types --------------------------------------------------===//
+
+// 'short _Accum'
+SIGNED_TYPE(ShortAccum, ShortAccumTy)
+
+// '_Accum'
+SIGNED_TYPE(Accum, AccumTy)
+
+// 'long _Accum'
+SIGNED_TYPE(LongAccum, LongAccumTy)
+
+// 'unsigned short _Accum'
+UNSIGNED_TYPE(UShortAccum, UnsignedShortAccumTy)
+
+// 'unsigned _Accum'
+UNSIGNED_TYPE(UAccum, UnsignedAccumTy)
+
+// 'unsigned long _Accum'
+UNSIGNED_TYPE(ULongAccum, UnsignedLongAccumTy)
+
 //===- Floating point types -----------------------------------------------===//
 
 // 'half' in OpenCL, '__fp16' in ARM NEON.
Index: include/clang/Basic/DiagnosticCommonKinds.td
===================================================================
--- include/clang/Basic/DiagnosticCommonKinds.td
+++ include/clang/Basic/DiagnosticCommonKinds.td
@@ -168,6 +168,8 @@
                           InGroup<GccCompat>;
 def ext_clang_diagnose_if : Extension<"'diagnose_if' is a clang extension">,
                             InGroup<GccCompat>;
+def err_fixed_point_only_allowed_in_c : Error<
+  "Fixed point types are only allowed in C">;
 
 // SEH
 def err_seh_expected_handler : Error<
Index: include/clang/Basic/Specifiers.h
===================================================================
--- include/clang/Basic/Specifiers.h
+++ include/clang/Basic/Specifiers.h
@@ -54,6 +54,7 @@
     TST_int128,
     TST_half,         // OpenCL half, ARM NEON __fp16
     TST_Float16,      // C11 extension ISO/IEC TS 18661-3
+    TST_Accum,        // ISO/IEC JTC1 SC22 WG14 N1169 Extension
     TST_float,
     TST_double,
     TST_float128,
Index: include/clang/Basic/TokenKinds.def
===================================================================
--- include/clang/Basic/TokenKinds.def
+++ include/clang/Basic/TokenKinds.def
@@ -389,6 +389,9 @@
 // C11 Extension
 KEYWORD(_Float16                    , KEYALL)
 
+// ISO/IEC JTC1 SC22 WG14 N1169 Extension
+KEYWORD(_Accum                      , KEYALL)
+
 // GNU Extensions (in impl-reserved namespace)
 KEYWORD(_Decimal32                  , KEYALL)
 KEYWORD(_Decimal64                  , KEYALL)
Index: include/clang/Sema/DeclSpec.h
===================================================================
--- include/clang/Sema/DeclSpec.h
+++ include/clang/Sema/DeclSpec.h
@@ -282,6 +282,7 @@
   static const TST TST_float = clang::TST_float;
   static const TST TST_double = clang::TST_double;
   static const TST TST_float16 = clang::TST_Float16;
+  static const TST TST_accum = clang::TST_Accum;
   static const TST TST_float128 = clang::TST_float128;
   static const TST TST_bool = clang::TST_bool;
   static const TST TST_decimal32 = clang::TST_decimal32;
Index: include/clang/Serialization/ASTBitCodes.h
===================================================================
--- include/clang/Serialization/ASTBitCodes.h
+++ include/clang/Serialization/ASTBitCodes.h
@@ -939,6 +939,26 @@
       /// The C++ 'char8_t' type.
       PREDEF_TYPE_CHAR8_ID = 45,
 
+      /// \brief The 'short _Accum' type
+      PREDEF_TYPE_SHORT_ACCUM_ID    = 46,
+
+      /// \brief The '_Accum' type
+      PREDEF_TYPE_ACCUM_ID      = 47,
+
+      /// \brief The 'long _Accum' type
+      PREDEF_TYPE_LONG_ACCUM_ID = 48,
+
+      /// \brief The 'unsigned short _Accum' type
+      PREDEF_TYPE_USHORT_ACCUM_ID   = 49,
+
+      /// \brief The 'unsigned _Accum' type
+      PREDEF_TYPE_UACCUM_ID     = 50,
+
+      /// \brief The 'unsigned long _Accum' type
+      PREDEF_TYPE_ULONG_ACCUM_ID    = 51,
+
+      /// \brief OpenCL image types with auto numeration
+
       /// OpenCL image types with auto numeration
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
       PREDEF_TYPE_##Id##_ID,
Index: lib/AST/ASTContext.cpp
===================================================================
--- lib/AST/ASTContext.cpp
+++ lib/AST/ASTContext.cpp
@@ -1134,6 +1134,14 @@
   // C11 extension ISO/IEC TS 18661-3
   InitBuiltinType(Float16Ty,           BuiltinType::Float16);
 
+  // ISO/IEC JTC1 SC22 WG14 N1169 Extension
+  InitBuiltinType(ShortAccumTy,         BuiltinType::ShortAccum);
+  InitBuiltinType(AccumTy,              BuiltinType::Accum);
+  InitBuiltinType(LongAccumTy,          BuiltinType::LongAccum);
+  InitBuiltinType(UnsignedShortAccumTy, BuiltinType::UShortAccum);
+  InitBuiltinType(UnsignedAccumTy,      BuiltinType::UAccum);
+  InitBuiltinType(UnsignedLongAccumTy,  BuiltinType::ULongAccum);
+
   // GNU extension, 128-bit integers.
   InitBuiltinType(Int128Ty,            BuiltinType::Int128);
   InitBuiltinType(UnsignedInt128Ty,    BuiltinType::UInt128);
@@ -1762,16 +1770,22 @@
       break;
     case BuiltinType::UShort:
     case BuiltinType::Short:
+    case BuiltinType::ShortAccum:
+    case BuiltinType::UShortAccum:
       Width = Target->getShortWidth();
       Align = Target->getShortAlign();
       break;
     case BuiltinType::UInt:
     case BuiltinType::Int:
+    case BuiltinType::Accum:
+    case BuiltinType::UAccum:
       Width = Target->getIntWidth();
       Align = Target->getIntAlign();
       break;
     case BuiltinType::ULong:
     case BuiltinType::Long:
+    case BuiltinType::LongAccum:
+    case BuiltinType::ULongAccum:
       Width = Target->getLongWidth();
       Align = Target->getLongAlign();
       break;
@@ -6230,6 +6244,14 @@
     case BuiltinType::ObjCSel:
       llvm_unreachable("@encoding ObjC primitive type");
 
+    case BuiltinType::ShortAccum:
+    case BuiltinType::Accum:
+    case BuiltinType::LongAccum:
+    case BuiltinType::UShortAccum:
+    case BuiltinType::UAccum:
+    case BuiltinType::ULongAccum:
+      llvm_unreachable("No ObjC encoding for fixed point types");
+
     // OpenCL and placeholder types don't need @encodings.
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
     case BuiltinType::Id:
Index: lib/AST/ExprConstant.cpp
===================================================================
--- lib/AST/ExprConstant.cpp
+++ lib/AST/ExprConstant.cpp
@@ -7331,6 +7331,9 @@
     case BuiltinType::ULong:
     case BuiltinType::ULongLong:
     case BuiltinType::UInt128:
+    case BuiltinType::UShortAccum:
+    case BuiltinType::UAccum:
+    case BuiltinType::ULongAccum:
       return integer_type_class;
 
     case BuiltinType::NullPtr:
Index: lib/AST/ItaniumMangle.cpp
===================================================================
--- lib/AST/ItaniumMangle.cpp
+++ lib/AST/ItaniumMangle.cpp
@@ -2552,6 +2552,13 @@
   case BuiltinType::Float16:
     Out << "DF16_";
     break;
+  case BuiltinType::ShortAccum:
+  case BuiltinType::Accum:
+  case BuiltinType::LongAccum:
+  case BuiltinType::UShortAccum:
+  case BuiltinType::UAccum:
+  case BuiltinType::ULongAccum:
+    llvm_unreachable("Fixed point types are disabled for c++");
   case BuiltinType::Half:
     Out << "Dh";
     break;
Index: lib/AST/MicrosoftMangle.cpp
===================================================================
--- lib/AST/MicrosoftMangle.cpp
+++ lib/AST/MicrosoftMangle.cpp
@@ -1926,6 +1926,12 @@
     mangleArtificalTagType(TTK_Struct, "_Half", {"__clang"});
     break;
 
+  case BuiltinType::ShortAccum:
+  case BuiltinType::Accum:
+  case BuiltinType::LongAccum:
+  case BuiltinType::UShortAccum:
+  case BuiltinType::UAccum:
+  case BuiltinType::ULongAccum:
   case BuiltinType::Char8:
   case BuiltinType::Float128: {
     DiagnosticsEngine &Diags = Context.getDiags();
Index: lib/AST/NSAPI.cpp
===================================================================
--- lib/AST/NSAPI.cpp
+++ lib/AST/NSAPI.cpp
@@ -441,6 +441,12 @@
   case BuiltinType::Char32:
   case BuiltinType::Int128:
   case BuiltinType::LongDouble:
+  case BuiltinType::ShortAccum:
+  case BuiltinType::Accum:
+  case BuiltinType::LongAccum:
+  case BuiltinType::UShortAccum:
+  case BuiltinType::UAccum:
+  case BuiltinType::ULongAccum:
   case BuiltinType::UInt128:
   case BuiltinType::Float16:
   case BuiltinType::Float128:
Index: lib/AST/Type.cpp
===================================================================
--- lib/AST/Type.cpp
+++ lib/AST/Type.cpp
@@ -2656,6 +2656,18 @@
     return "double";
   case LongDouble:
     return "long double";
+  case ShortAccum:
+    return "short _Accum";
+  case Accum:
+    return "_Accum";
+  case LongAccum:
+    return "long _Accum";
+  case UShortAccum:
+    return "unsigned short _Accum";
+  case UAccum:
+    return "unsigned _Accum";
+  case ULongAccum:
+    return "unsigned long _Accum";
   case Float16:
     return "_Float16";
   case Float128:
Index: lib/AST/TypeLoc.cpp
===================================================================
--- lib/AST/TypeLoc.cpp
+++ lib/AST/TypeLoc.cpp
@@ -344,6 +344,12 @@
   case BuiltinType::LongDouble:
   case BuiltinType::Float16:
   case BuiltinType::Float128:
+  case BuiltinType::ShortAccum:
+  case BuiltinType::Accum:
+  case BuiltinType::LongAccum:
+  case BuiltinType::UShortAccum:
+  case BuiltinType::UAccum:
+  case BuiltinType::ULongAccum:
     llvm_unreachable("Builtin type needs extra local data!");
     // Fall through, if the impossible happens.
       
Index: lib/Analysis/PrintfFormatString.cpp
===================================================================
--- lib/Analysis/PrintfFormatString.cpp
+++ lib/Analysis/PrintfFormatString.cpp
@@ -655,6 +655,12 @@
   case BuiltinType::Half:
   case BuiltinType::Float16:
   case BuiltinType::Float128:
+  case BuiltinType::ShortAccum:
+  case BuiltinType::Accum:
+  case BuiltinType::LongAccum:
+  case BuiltinType::UShortAccum:
+  case BuiltinType::UAccum:
+  case BuiltinType::ULongAccum:
     // Various types which are non-trivial to correct.
     return false;
 
Index: lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- lib/CodeGen/CGDebugInfo.cpp
+++ lib/CodeGen/CGDebugInfo.cpp
@@ -676,6 +676,9 @@
   case BuiltinType::ULong:
   case BuiltinType::WChar_U:
   case BuiltinType::ULongLong:
+  case BuiltinType::UShortAccum:
+  case BuiltinType::UAccum:
+  case BuiltinType::ULongAccum:
     Encoding = llvm::dwarf::DW_ATE_unsigned;
     break;
   case BuiltinType::Short:
@@ -684,6 +687,9 @@
   case BuiltinType::Long:
   case BuiltinType::WChar_S:
   case BuiltinType::LongLong:
+  case BuiltinType::ShortAccum:
+  case BuiltinType::Accum:
+  case BuiltinType::LongAccum:
     Encoding = llvm::dwarf::DW_ATE_signed;
     break;
   case BuiltinType::Bool:
Index: lib/CodeGen/CodeGenTypes.cpp
===================================================================
--- lib/CodeGen/CodeGenTypes.cpp
+++ lib/CodeGen/CodeGenTypes.cpp
@@ -440,6 +440,13 @@
     case BuiltinType::Char8:
     case BuiltinType::Char16:
     case BuiltinType::Char32:
+    case BuiltinType::ShortAccum:
+    case BuiltinType::Accum:
+    case BuiltinType::LongAccum:
+    case BuiltinType::UShortAccum:
+    case BuiltinType::UAccum:
+    case BuiltinType::ULongAccum:
+      // TODO: Use a different dwarf type for _Accum
       ResultType = llvm::IntegerType::get(getLLVMContext(),
                                  static_cast<unsigned>(Context.getTypeSize(T)));
       break;
Index: lib/CodeGen/ItaniumCXXABI.cpp
===================================================================
--- lib/CodeGen/ItaniumCXXABI.cpp
+++ lib/CodeGen/ItaniumCXXABI.cpp
@@ -2709,6 +2709,12 @@
     case BuiltinType::Char32:
     case BuiltinType::Int128:
     case BuiltinType::UInt128:
+    case BuiltinType::ShortAccum:
+    case BuiltinType::Accum:
+    case BuiltinType::LongAccum:
+    case BuiltinType::UShortAccum:
+    case BuiltinType::UAccum:
+    case BuiltinType::ULongAccum:
       return true;
 
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
Index: lib/Index/USRGeneration.cpp
===================================================================
--- lib/Index/USRGeneration.cpp
+++ lib/Index/USRGeneration.cpp
@@ -642,61 +642,105 @@
     }
     
     if (const BuiltinType *BT = T->getAs<BuiltinType>()) {
-      unsigned char c = '\0';
       switch (BT->getKind()) {
         case BuiltinType::Void:
-          c = 'v'; break;
+          Out << 'v';
+          return;
         case BuiltinType::Bool:
-          c = 'b'; break;
+          Out << 'b';
+          return;
         case BuiltinType::UChar:
-          c = 'c'; break;
+          Out << 'c';
+          return;
         case BuiltinType::Char8:
-          c = 'u'; break; // FIXME: Check this doesn't collide
+          Out << 'u';
+          return; // FIXME: Check this doesn't collide
         case BuiltinType::Char16:
-          c = 'q'; break;
+          Out << 'q';
+          return;
         case BuiltinType::Char32:
-          c = 'w'; break;
+          Out << 'w';
+          return;
         case BuiltinType::UShort:
-          c = 's'; break;
+          Out << 's';
+          return;
         case BuiltinType::UInt:
-          c = 'i'; break;
+          Out << 'i';
+          return;
         case BuiltinType::ULong:
-          c = 'l'; break;
+          Out << 'l';
+          return;
         case BuiltinType::ULongLong:
-          c = 'k'; break;
+          Out << 'k';
+          return;
         case BuiltinType::UInt128:
-          c = 'j'; break;
+          Out << 'j';
+          return;
         case BuiltinType::Char_U:
         case BuiltinType::Char_S:
-          c = 'C'; break;
+          Out << 'C';
+          return;
         case BuiltinType::SChar:
-          c = 'r'; break;
+          Out << 'r';
+          return;
         case BuiltinType::WChar_S:
         case BuiltinType::WChar_U:
-          c = 'W'; break;
+          Out << 'W';
+          return;
         case BuiltinType::Short:
-          c = 'S'; break;
+          Out << 'S';
+          return;
         case BuiltinType::Int:
-          c = 'I'; break;
+          Out << 'I';
+          return;
         case BuiltinType::Long:
-          c = 'L'; break;
+          Out << 'L';
+          return;
         case BuiltinType::LongLong:
-          c = 'K'; break;
+          Out << 'K';
+          return;
         case BuiltinType::Int128:
-          c = 'J'; break;
+          Out << 'J';
+          return;
+        case BuiltinType::ShortAccum:
+          // ~ is a special character to indicate we have a fixed point type
+          // that will be followed by further characters to indicate the type.
+          Out << "~sA";
+          return;
+        case BuiltinType::Accum:
+          Out << "~A";
+          return;
+        case BuiltinType::LongAccum:
+          Out << "~lA";
+          return;
+        case BuiltinType::UShortAccum:
+          Out << "~UsA";
+          return;
+        case BuiltinType::UAccum:
+          Out << "~UA";
+          return;
+        case BuiltinType::ULongAccum:
+          Out << "~UlA";
+          return;
         case BuiltinType::Float16:
         case BuiltinType::Half:
-          c = 'h'; break;
+          Out << 'h';
+          return;
         case BuiltinType::Float:
-          c = 'f'; break;
+          Out << 'f';
+          return;
         case BuiltinType::Double:
-          c = 'd'; break;
+          Out << 'd';
+          return;
         case BuiltinType::LongDouble:
-          c = 'D'; break;
+          Out << 'D';
+          return;
         case BuiltinType::Float128:
-          c = 'Q'; break;
+          Out << 'Q';
+          return;
         case BuiltinType::NullPtr:
-          c = 'n'; break;
+          Out << 'n';
+          return;
 #define BUILTIN_TYPE(Id, SingletonId)
 #define PLACEHOLDER_TYPE(Id, SingletonId) case BuiltinType::Id:
 #include "clang/AST/BuiltinTypes.def"
@@ -712,14 +756,15 @@
           IgnoreResults = true;
           return;
         case BuiltinType::ObjCId:
-          c = 'o'; break;
+          Out << 'o';
+          return;
         case BuiltinType::ObjCClass:
-          c = 'O'; break;
+          Out << 'O';
+          return;
         case BuiltinType::ObjCSel:
-          c = 'e'; break;
+          Out << 'e';
+          return;
       }
-      Out << c;
-      return;
     }
 
     // If we have already seen this (non-built-in) type, use a substitution
Index: lib/Parse/ParseDecl.cpp
===================================================================
--- lib/Parse/ParseDecl.cpp
+++ lib/Parse/ParseDecl.cpp
@@ -3580,6 +3580,10 @@
       isInvalid = DS.SetTypeSpecType(DeclSpec::TST_float16, Loc, PrevSpec,
                                      DiagID, Policy);
       break;
+    case tok::kw__Accum:
+      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_accum, Loc, PrevSpec, DiagID,
+                                     Policy);
+      break;
     case tok::kw___float128:
       isInvalid = DS.SetTypeSpecType(DeclSpec::TST_float128, Loc, PrevSpec,
                                      DiagID, Policy);
@@ -4606,6 +4610,7 @@
   case tok::kw_half:
   case tok::kw_float:
   case tok::kw_double:
+  case tok::kw__Accum:
   case tok::kw__Float16:
   case tok::kw___float128:
   case tok::kw_bool:
@@ -4683,6 +4688,7 @@
   case tok::kw_half:
   case tok::kw_float:
   case tok::kw_double:
+  case tok::kw__Accum:
   case tok::kw__Float16:
   case tok::kw___float128:
   case tok::kw_bool:
@@ -4841,6 +4847,7 @@
   case tok::kw_half:
   case tok::kw_float:
   case tok::kw_double:
+  case tok::kw__Accum:
   case tok::kw__Float16:
   case tok::kw___float128:
   case tok::kw_bool:
Index: lib/Sema/DeclSpec.cpp
===================================================================
--- lib/Sema/DeclSpec.cpp
+++ lib/Sema/DeclSpec.cpp
@@ -339,6 +339,7 @@
     case TST_decimal32:
     case TST_decimal64:
     case TST_double:
+    case TST_Accum:
     case TST_Float16:
     case TST_float128:
     case TST_enum:
@@ -510,6 +511,7 @@
   case DeclSpec::TST_half:        return "half";
   case DeclSpec::TST_float:       return "float";
   case DeclSpec::TST_double:      return "double";
+  case DeclSpec::TST_accum:       return "_Accum";
   case DeclSpec::TST_float16:     return "_Float16";
   case DeclSpec::TST_float128:    return "__float128";
   case DeclSpec::TST_bool:        return Policy.Bool ? "bool" : "_Bool";
@@ -1100,12 +1102,13 @@
     }
   }
 
-  // signed/unsigned are only valid with int/char/wchar_t.
+  // signed/unsigned are only valid with int/char/wchar_t/_Accum.
   if (TypeSpecSign != TSS_unspecified) {
     if (TypeSpecType == TST_unspecified)
       TypeSpecType = TST_int; // unsigned -> unsigned int, signed -> signed int.
-    else if (TypeSpecType != TST_int  && TypeSpecType != TST_int128 &&
-             TypeSpecType != TST_char && TypeSpecType != TST_wchar) {
+    else if (TypeSpecType != TST_int && TypeSpecType != TST_int128 &&
+             TypeSpecType != TST_char && TypeSpecType != TST_wchar &&
+             TypeSpecType != TST_accum) {
       S.Diag(TSSLoc, diag::err_invalid_sign_spec)
         << getSpecifierName((TST)TypeSpecType, Policy);
       // signed double -> double.
@@ -1120,7 +1123,8 @@
   case TSW_longlong: // long long int
     if (TypeSpecType == TST_unspecified)
       TypeSpecType = TST_int; // short -> short int, long long -> long long int.
-    else if (TypeSpecType != TST_int) {
+    else if (!(TypeSpecType == TST_int ||
+               (TypeSpecType == TST_accum && TypeSpecWidth != TSW_longlong))) {
       S.Diag(TSWRange.getBegin(), diag::err_invalid_width_spec)
           << (int)TypeSpecWidth << getSpecifierName((TST)TypeSpecType, Policy);
       TypeSpecType = TST_int;
@@ -1130,7 +1134,8 @@
   case TSW_long:  // long double, long int
     if (TypeSpecType == TST_unspecified)
       TypeSpecType = TST_int;  // long -> long int.
-    else if (TypeSpecType != TST_int && TypeSpecType != TST_double) {
+    else if (TypeSpecType != TST_int && TypeSpecType != TST_double &&
+             TypeSpecType != TST_accum) {
       S.Diag(TSWRange.getBegin(), diag::err_invalid_width_spec)
           << (int)TypeSpecWidth << getSpecifierName((TST)TypeSpecType, Policy);
       TypeSpecType = TST_int;
Index: lib/Sema/SemaTemplateVariadic.cpp
===================================================================
--- lib/Sema/SemaTemplateVariadic.cpp
+++ lib/Sema/SemaTemplateVariadic.cpp
@@ -830,6 +830,7 @@
   case TST_half:
   case TST_float:
   case TST_double:
+  case TST_Accum:
   case TST_Float16:
   case TST_float128:
   case TST_bool:
Index: lib/Sema/SemaType.cpp
===================================================================
--- lib/Sema/SemaType.cpp
+++ lib/Sema/SemaType.cpp
@@ -1391,6 +1391,48 @@
     }
     break;
   }
+  case DeclSpec::TST_accum: {
+    if (S.getLangOpts().CPlusPlus) {
+      S.Diag(DS.getTypeSpecTypeLoc(), diag::err_fixed_point_only_allowed_in_c);
+      Result = Context.ShortAccumTy;
+      break;
+    }
+
+    if (DS.getTypeSpecSign() != DeclSpec::TSS_unsigned) {
+      switch (DS.getTypeSpecWidth()) {
+        case DeclSpec::TSW_short:
+          Result = Context.ShortAccumTy;
+          break;
+        case DeclSpec::TSW_unspecified:
+          Result = Context.AccumTy;
+          break;
+        case DeclSpec::TSW_long:
+          Result = Context.LongAccumTy;
+          break;
+        case DeclSpec::TSW_longlong:
+          // Unreachable b/c this is caught in final analysis of the DeclSpec.
+          llvm_unreachable("Unable to specify long long as _Accum width");
+          break;
+      }
+    } else {
+      switch (DS.getTypeSpecWidth()) {
+        case DeclSpec::TSW_short:
+          Result = Context.UnsignedShortAccumTy;
+          break;
+        case DeclSpec::TSW_unspecified:
+          Result = Context.UnsignedAccumTy;
+          break;
+        case DeclSpec::TSW_long:
+          Result = Context.UnsignedLongAccumTy;
+          break;
+        case DeclSpec::TSW_longlong:
+          // TODO: Replace with diag
+          llvm_unreachable("Unable to specify long long as _Accum width");
+          break;
+      }
+    }
+    break;
+  }
   case DeclSpec::TST_int128:
     if (!S.Context.getTargetInfo().hasInt128Type())
       S.Diag(DS.getTypeSpecTypeLoc(), diag::err_type_unsupported)
Index: lib/Serialization/ASTCommon.cpp
===================================================================
--- lib/Serialization/ASTCommon.cpp
+++ lib/Serialization/ASTCommon.cpp
@@ -91,6 +91,24 @@
   case BuiltinType::LongDouble:
     ID = PREDEF_TYPE_LONGDOUBLE_ID;
     break;
+  case BuiltinType::ShortAccum:
+    ID = PREDEF_TYPE_SHORT_ACCUM_ID;
+    break;
+  case BuiltinType::Accum:
+    ID = PREDEF_TYPE_ACCUM_ID;
+    break;
+  case BuiltinType::LongAccum:
+    ID = PREDEF_TYPE_LONG_ACCUM_ID;
+    break;
+  case BuiltinType::UShortAccum:
+    ID = PREDEF_TYPE_USHORT_ACCUM_ID;
+    break;
+  case BuiltinType::UAccum:
+    ID = PREDEF_TYPE_UACCUM_ID;
+    break;
+  case BuiltinType::ULongAccum:
+    ID = PREDEF_TYPE_ULONG_ACCUM_ID;
+    break;
   case BuiltinType::Float16:
     ID = PREDEF_TYPE_FLOAT16_ID;
     break;
Index: lib/Serialization/ASTReader.cpp
===================================================================
--- lib/Serialization/ASTReader.cpp
+++ lib/Serialization/ASTReader.cpp
@@ -6818,6 +6818,24 @@
     case PREDEF_TYPE_LONGDOUBLE_ID:
       T = Context.LongDoubleTy;
       break;
+    case PREDEF_TYPE_SHORT_ACCUM_ID:
+      T = Context.ShortAccumTy;
+      break;
+    case PREDEF_TYPE_ACCUM_ID:
+      T = Context.AccumTy;
+      break;
+    case PREDEF_TYPE_LONG_ACCUM_ID:
+      T = Context.LongAccumTy;
+      break;
+    case PREDEF_TYPE_USHORT_ACCUM_ID:
+      T = Context.UnsignedShortAccumTy;
+      break;
+    case PREDEF_TYPE_UACCUM_ID:
+      T = Context.UnsignedAccumTy;
+      break;
+    case PREDEF_TYPE_ULONG_ACCUM_ID:
+      T = Context.UnsignedLongAccumTy;
+      break;
     case PREDEF_TYPE_FLOAT16_ID:
       T = Context.Float16Ty;
       break;
Index: test/Frontend/accum.c
===================================================================
--- /dev/null
+++ test/Frontend/accum.c
@@ -0,0 +1,26 @@
+// RUN: %clang -cc1 -x c -ast-dump %s | FileCheck %s --strict-whitespace
+
+/*  Various contexts where type _Accum can appear. */
+
+// Primary fixed point types
+signed short _Accum s_short_accum;
+signed _Accum s_accum;
+signed long _Accum s_long_accum;
+unsigned short _Accum u_short_accum;
+unsigned _Accum u_accum;
+unsigned long _Accum u_long_accum;
+
+// Aliased fixed point types
+short _Accum short_accum;
+_Accum accum;
+long _Accum long_accum;
+
+// CHECK:      |-VarDecl {{.*}} s_short_accum 'short _Accum'
+// CHECK-NEXT: |-VarDecl {{.*}} s_accum '_Accum'
+// CHECK-NEXT: |-VarDecl {{.*}} s_long_accum 'long _Accum'
+// CHECK-NEXT: |-VarDecl {{.*}} u_short_accum 'unsigned short _Accum'
+// CHECK-NEXT: |-VarDecl {{.*}} u_accum 'unsigned _Accum'
+// CHECK-NEXT: |-VarDecl {{.*}} u_long_accum 'unsigned long _Accum'
+// CHECK-NEXT: |-VarDecl {{.*}} short_accum 'short _Accum'
+// CHECK-NEXT: |-VarDecl {{.*}} accum '_Accum'
+// CHECK-NEXT: `-VarDecl {{.*}} long_accum 'long _Accum'
Index: test/Frontend/accum_errors.c
===================================================================
--- /dev/null
+++ test/Frontend/accum_errors.c
@@ -0,0 +1,4 @@
+// RUN: %clang_cc1 -x c -fsyntax-only -verify -pedantic %s
+
+long long _Accum longlong_accum;  // expected-error{{'long long _Accum' is invalid}}
+unsigned long long _Accum u_longlong_accum;  // expected-error{{'long long _Accum' is invalid}}
Index: test/Frontend/accum_errors.cpp
===================================================================
--- /dev/null
+++ test/Frontend/accum_errors.cpp
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -x c++ %s -verify
+
+// Name namgling is not provided for fixed point types in c++
+
+signed short _Accum s_short_accum;  // expected-error{{Fixed point types are only allowed in C}}
+signed _Accum s_accum;  // expected-error{{Fixed point types are only allowed in C}}
+signed long _Accum s_long_accum;  // expected-error{{Fixed point types are only allowed in C}}
+unsigned short _Accum u_short_accum;  // expected-error{{Fixed point types are only allowed in C}}
+unsigned _Accum u_accum;  // expected-error{{Fixed point types are only allowed in C}}
+unsigned long _Accum u_long_accum;  // expected-error{{Fixed point types are only allowed in C}}
+
+short _Accum short_accum;  // expected-error{{Fixed point types are only allowed in C}}
+_Accum accum;     // expected-error{{Fixed point types are only allowed in C}}
+long _Accum long_accum;  // expected-error{{Fixed point types are only allowed in C}}
Index: tools/libclang/CXType.cpp
===================================================================
--- tools/libclang/CXType.cpp
+++ tools/libclang/CXType.cpp
@@ -53,6 +53,12 @@
     BTCASE(Float);
     BTCASE(Double);
     BTCASE(LongDouble);
+    BTCASE(ShortAccum);
+    BTCASE(Accum);
+    BTCASE(LongAccum);
+    BTCASE(UShortAccum);
+    BTCASE(UAccum);
+    BTCASE(ULongAccum);
     BTCASE(Float16);
     BTCASE(Float128);
     BTCASE(NullPtr);
@@ -546,6 +552,12 @@
     TKIND(Float);
     TKIND(Double);
     TKIND(LongDouble);
+    TKIND(ShortAccum);
+    TKIND(Accum);
+    TKIND(LongAccum);
+    TKIND(UShortAccum);
+    TKIND(UAccum);
+    TKIND(ULongAccum);
     TKIND(Float16);
     TKIND(Float128);
     TKIND(NullPtr);