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 +168,10 @@
                           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">;
+def err_fixed_point_not_enabled : Error<"compile with "
+  "'-enable-fixed-point' to enable fixed point types">;
 
 // SEH
 def err_seh_expected_handler : Error<
Index: include/clang/Basic/LangOptions.def
===================================================================
--- include/clang/Basic/LangOptions.def
+++ include/clang/Basic/LangOptions.def
@@ -298,6 +298,8 @@
 
 COMPATIBLE_VALUE_LANGOPT(FunctionAlignment, 5, 0, "Default alignment for functions")
 
+LANGOPT(FixedPointEnabled, 1, 0, "Fixed point types are enabled")
+
 #undef LANGOPT
 #undef COMPATIBLE_LANGOPT
 #undef BENIGN_LANGOPT
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/TargetInfo.h
===================================================================
--- include/clang/Basic/TargetInfo.h
+++ include/clang/Basic/TargetInfo.h
@@ -74,6 +74,9 @@
   unsigned char LargeArrayMinWidth, LargeArrayAlign;
   unsigned char LongWidth, LongAlign;
   unsigned char LongLongWidth, LongLongAlign;
+  unsigned char ShortAccumWidth, ShortAccumAlign;
+  unsigned char AccumWidth, AccumAlign;
+  unsigned char LongAccumWidth, LongAccumAlign;
   unsigned char SuitableAlign;
   unsigned char DefaultAlignForAttributeAligned;
   unsigned char MinGlobalAlign;
@@ -358,6 +361,21 @@
   unsigned getLongLongWidth() const { return LongLongWidth; }
   unsigned getLongLongAlign() const { return LongLongAlign; }
 
+  /// getShortAccumWidth/Align - Return the size of 'signed short _Accum' and
+  /// 'unsigned short _Accum' for this target, in bits.
+  unsigned getShortAccumWidth() const { return ShortAccumWidth; }
+  unsigned getShortAccumAlign() const { return ShortAccumAlign; }
+
+  /// getAccumWidth/Align - Return the size of 'signed _Accum' and
+  /// 'unsigned _Accum' for this target, in bits.
+  unsigned getAccumWidth() const { return AccumWidth; }
+  unsigned getAccumAlign() const { return AccumAlign; }
+
+  /// getLongAccumWidth/Align - Return the size of 'signed long _Accum' and
+  /// 'unsigned long _Accum' for this target, in bits.
+  unsigned getLongAccumWidth() const { return LongAccumWidth; }
+  unsigned getLongAccumAlign() const { return LongAccumAlign; }
+
   /// Determine whether the __int128 type is supported on this target.
   virtual bool hasInt128Type() const {
     return (getPointerWidth(0) >= 64) || getTargetOpts().ForceEnableInt128;
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/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -118,6 +118,10 @@
 def f_Group : OptionGroup<"<f group>">, Group<CompileOnly_Group>,
               DocName<"Target-independent compilation options">;
 
+def fixed_point_Group : OptionGroup<"<fixed point group>">,
+                        Group<CompileOnly_Group>,
+                        DocName<"Fixed Point Flags">;
+
 def f_clang_Group : OptionGroup<"<f (clang-only) group>">,
                     Group<CompileOnly_Group>, DocFlatten;
 def pedantic_Group : OptionGroup<"<pedantic group>">, Group<f_Group>,
@@ -875,6 +879,9 @@
   Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Disable support for int128_t type">;
 
+def enable_fixed_point : Flag<["-", "--"], "enable-fixed-point">, Group<fixed_point_Group>,
+                         Flags<[CC1Option]>, HelpText<"Enable fixed point types">;
+
 // Begin sanitizer flags. These should all be core options exposed in all driver
 // modes.
 let Flags = [CC1Option, CoreOption] in {
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);
@@ -1785,6 +1793,21 @@
       Width = 128;
       Align = 128; // int128_t is 128-bit aligned on all targets.
       break;
+    case BuiltinType::ShortAccum:
+    case BuiltinType::UShortAccum:
+      Width = Target->getShortAccumWidth();
+      Align = Target->getShortAccumAlign();
+      break;
+    case BuiltinType::Accum:
+    case BuiltinType::UAccum:
+      Width = Target->getAccumWidth();
+      Align = Target->getAccumAlign();
+      break;
+    case BuiltinType::LongAccum:
+    case BuiltinType::ULongAccum:
+      Width = Target->getLongAccumWidth();
+      Align = Target->getLongAccumAlign();
+      break;
     case BuiltinType::Float16:
     case BuiltinType::Half:
       Width = Target->getHalfWidth();
@@ -6222,6 +6245,12 @@
     case BuiltinType::Float16:
     case BuiltinType::Float128:
     case BuiltinType::Half:
+    case BuiltinType::ShortAccum:
+    case BuiltinType::Accum:
+    case BuiltinType::LongAccum:
+    case BuiltinType::UShortAccum:
+    case BuiltinType::UAccum:
+    case BuiltinType::ULongAccum:
       // FIXME: potentially need @encodes for these!
       return ' ';
 
Index: lib/AST/ExprConstant.cpp
===================================================================
--- lib/AST/ExprConstant.cpp
+++ lib/AST/ExprConstant.cpp
@@ -7355,6 +7355,13 @@
     case BuiltinType::UInt128:
       return GCCTypeClass::Integer;
 
+    case BuiltinType::UShortAccum:
+    case BuiltinType::UAccum:
+    case BuiltinType::ULongAccum:
+      // GCC does not cover FIXED_POINT_TYPE in it's switch stmt and defaults to
+      // no_type_class
+      return GCCTypeClass::None;
+
     case BuiltinType::NullPtr:
 
     case BuiltinType::ObjCId:
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/Basic/TargetInfo.cpp
===================================================================
--- lib/Basic/TargetInfo.cpp
+++ lib/Basic/TargetInfo.cpp
@@ -40,6 +40,9 @@
   IntWidth = IntAlign = 32;
   LongWidth = LongAlign = 32;
   LongLongWidth = LongLongAlign = 64;
+  ShortAccumWidth = ShortAccumAlign = 16;
+  AccumWidth = AccumAlign = 32;
+  LongAccumWidth = LongAccumAlign = 64;
   SuitableAlign = 64;
   DefaultAlignForAttributeAligned = 128;
   MinGlobalAlign = 0;
Index: lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- lib/CodeGen/CGDebugInfo.cpp
+++ lib/CodeGen/CGDebugInfo.cpp
@@ -702,6 +702,16 @@
     // floating point types of the same size.
     Encoding = llvm::dwarf::DW_ATE_float;
     break;
+  case BuiltinType::ShortAccum:
+  case BuiltinType::Accum:
+  case BuiltinType::LongAccum:
+    Encoding = llvm::dwarf::DW_ATE_signed_fixed;
+    break;
+  case BuiltinType::UShortAccum:
+  case BuiltinType::UAccum:
+  case BuiltinType::ULongAccum:
+    Encoding = llvm::dwarf::DW_ATE_unsigned_fixed;
+    break;
   }
 
   switch (BT->getKind()) {
Index: lib/CodeGen/CodeGenTypes.cpp
===================================================================
--- lib/CodeGen/CodeGenTypes.cpp
+++ lib/CodeGen/CodeGenTypes.cpp
@@ -440,6 +440,12 @@
     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:
       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
@@ -2719,6 +2719,12 @@
     case BuiltinType::OCLClkEvent:
     case BuiltinType::OCLQueue:
     case BuiltinType::OCLReserveID:
+    case BuiltinType::ShortAccum:
+    case BuiltinType::Accum:
+    case BuiltinType::LongAccum:
+    case BuiltinType::UShortAccum:
+    case BuiltinType::UAccum:
+    case BuiltinType::ULongAccum:
       return false;
 
     case BuiltinType::Dependent:
Index: lib/Driver/ToolChains/Clang.cpp
===================================================================
--- lib/Driver/ToolChains/Clang.cpp
+++ lib/Driver/ToolChains/Clang.cpp
@@ -3756,6 +3756,10 @@
   Args.AddLastArg(CmdArgs, options::OPT_pedantic_errors);
   Args.AddLastArg(CmdArgs, options::OPT_w);
 
+  // Fixed point flags
+  if (Args.hasArg(options::OPT_enable_fixed_point))
+    Args.AddLastArg(CmdArgs, options::OPT_enable_fixed_point);
+
   // Handle -{std, ansi, trigraphs} -- take the last of -{std, ansi}
   // (-ansi is equivalent to -std=c89 or -std=c++98).
   //
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -2329,6 +2329,10 @@
   Opts.ObjCExceptions = Args.hasArg(OPT_fobjc_exceptions);
   Opts.CXXExceptions = Args.hasArg(OPT_fcxx_exceptions);
 
+  // -enable-fixed-point
+  Opts.FixedPointEnabled =
+      Args.hasArg(OPT_enable_fixed_point) && !Opts.CPlusPlus;
+
   // Handle exception personalities
   Arg *A = Args.getLastArg(options::OPT_fsjlj_exceptions,
                            options::OPT_fseh_exceptions,
Index: lib/Index/USRGeneration.cpp
===================================================================
--- lib/Index/USRGeneration.cpp
+++ lib/Index/USRGeneration.cpp
@@ -709,6 +709,12 @@
         case BuiltinType::OCLQueue:
         case BuiltinType::OCLReserveID:
         case BuiltinType::OCLSampler:
+        case BuiltinType::ShortAccum:
+        case BuiltinType::Accum:
+        case BuiltinType::LongAccum:
+        case BuiltinType::UShortAccum:
+        case BuiltinType::UAccum:
+        case BuiltinType::ULongAccum:
           IgnoreResults = true;
           return;
         case BuiltinType::ObjCId:
Index: lib/Parse/ParseDecl.cpp
===================================================================
--- lib/Parse/ParseDecl.cpp
+++ lib/Parse/ParseDecl.cpp
@@ -3580,6 +3580,19 @@
       isInvalid = DS.SetTypeSpecType(DeclSpec::TST_float16, Loc, PrevSpec,
                                      DiagID, Policy);
       break;
+    case tok::kw__Accum:
+      if (!getLangOpts().FixedPointEnabled) {
+        if (getLangOpts().CPlusPlus)
+          DiagID = diag::err_fixed_point_only_allowed_in_c;
+        else
+          DiagID = diag::err_fixed_point_not_enabled;
+        PrevSpec = "";  // Not used by diagnostic
+        isInvalid = true;
+      } else {
+        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 +4619,7 @@
   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 +4697,7 @@
   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 +4856,7 @@
   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 +1391,41 @@
     }
     break;
   }
+  case DeclSpec::TST_accum: {
+    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:
+          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
@@ -6819,6 +6819,24 @@
     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/fixed_point.c
===================================================================
--- /dev/null
+++ test/Frontend/fixed_point.c
@@ -0,0 +1,57 @@
+// RUN: %clang_cc1 -x c -enable-fixed-point -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'
+
+#define MIX_TYPE_SPEC(SPEC, SIGN, SIZE, ID) \
+  SPEC SIGN SIZE _Accum ID; \
+  SIGN SPEC SIZE _Accum ID ## 2; \
+  SIGN SIZE SPEC _Accum ID ## 3; \
+  SIGN SIZE _Accum SPEC ID ## 4;
+
+/* Mixing fixed point types with other type specifiers */
+
+#define MIX_VOLATILE(SIGN, SIZE, ID) MIX_TYPE_SPEC(volatile, SIGN, SIZE, ID)
+#define MIX_ATOMIC(SIGN, SIZE, ID) MIX_TYPE_SPEC(_Atomic, SIGN, SIZE, ID)
+#define MIX_CONST(SIGN, SIZE, ID) MIX_TYPE_SPEC(const, SIGN, SIZE, ID)
+
+MIX_VOLATILE(signed, short, vol_s_short_accum)
+MIX_ATOMIC(signed, short, atm_s_short_accum)
+MIX_CONST(signed, short, const_s_short_accum)
+
+// CHECK-NEXT: |-VarDecl {{.*}} vol_s_short_accum 'volatile short _Accum'
+// CHECK-NEXT: |-VarDecl {{.*}} vol_s_short_accum2 'volatile short _Accum'
+// CHECK-NEXT: |-VarDecl {{.*}} vol_s_short_accum3 'volatile short _Accum'
+// CHECK-NEXT: |-VarDecl {{.*}} vol_s_short_accum4 'volatile short _Accum'
+
+// CHECK-NEXT: |-VarDecl {{.*}} atm_s_short_accum '_Atomic(short _Accum)'
+// CHECK-NEXT: |-VarDecl {{.*}} atm_s_short_accum2 '_Atomic(short _Accum)'
+// CHECK-NEXT: |-VarDecl {{.*}} atm_s_short_accum3 '_Atomic(short _Accum)'
+// CHECK-NEXT: |-VarDecl {{.*}} atm_s_short_accum4 '_Atomic(short _Accum)'
+
+// CHECK-NEXT: |-VarDecl {{.*}} const_s_short_accum 'const short _Accum'
+// CHECK-NEXT: |-VarDecl {{.*}} const_s_short_accum2 'const short _Accum'
+// CHECK-NEXT: |-VarDecl {{.*}} const_s_short_accum3 'const short _Accum'
+// CHECK-NEXT: `-VarDecl {{.*}} const_s_short_accum4 'const short _Accum'
Index: test/Frontend/fixed_point_errors.c
===================================================================
--- /dev/null
+++ test/Frontend/fixed_point_errors.c
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -verify -enable-fixed-point %s
+
+/* We do not yet support long long. No recommended bit widths are given for this
+ * size. */
+
+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}}
+
+/* Although _Complex types work with floating point numbers, the extension
+ * provides no info for complex fixed point types. */
+
+_Complex signed short _Accum cmplx_s_short_accum;   // expected-error{{'_Complex _Accum' is invalid}}
+_Complex signed _Accum cmplx_s_accum;               // expected-error{{'_Complex _Accum' is invalid}}
+_Complex signed long _Accum cmplx_s_long_accum;     // expected-error{{'_Complex _Accum' is invalid}}
+_Complex unsigned short _Accum cmplx_u_short_accum; // expected-error{{'_Complex _Accum' is invalid}}
+_Complex unsigned _Accum cmplx_u_accum;             // expected-error{{'_Complex _Accum' is invalid}}
+_Complex unsigned long _Accum cmplx_u_long_accum;   // expected-error{{'_Complex _Accum' is invalid}}
+_Complex short _Accum cmplx_s_short_accum;          // expected-error{{'_Complex _Accum' is invalid}}
+_Complex _Accum cmplx_s_accum;                      // expected-error{{'_Complex _Accum' is invalid}}
+_Complex long _Accum cmplx_s_long_accum;            // expected-error{{'_Complex _Accum' is invalid}}
+
+/* Bad combinations */
+float _Accum f_accum;     // expected-error{{cannot combine with previous 'float' declaration specifier}}
+double _Accum d_accum;    // expected-error{{cannot combine with previous 'double' declaration specifier}}
+char _Accum c_accum;      // expected-error{{cannot combine with previous 'char' declaration specifier}}
+int _Accum i_accum;       // expected-error{{cannot combine with previous 'int' declaration specifier}}
Index: test/Frontend/fixed_point_errors.cpp
===================================================================
--- /dev/null
+++ test/Frontend/fixed_point_errors.cpp
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -x c++ -enable-fixed-point %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}}
+                                        // expected-error@-1{{C++ requires a type specifier for all declarations}}
+long _Accum long_accum;                 // expected-error{{fixed point types are only allowed in C}}
Index: test/Frontend/fixed_point_not_enabled.c
===================================================================
--- /dev/null
+++ test/Frontend/fixed_point_not_enabled.c
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -x c -verify %s
+
+// Primary fixed point types
+signed short _Accum s_short_accum;    // expected-error{{compile with '-enable-fixed-point' to enable fixed point types}}
+signed _Accum s_accum;                // expected-error{{compile with '-enable-fixed-point' to enable fixed point types}}
+signed long _Accum s_long_accum;      // expected-error{{compile with '-enable-fixed-point' to enable fixed point types}}
+unsigned short _Accum u_short_accum;  // expected-error{{compile with '-enable-fixed-point' to enable fixed point types}}
+unsigned _Accum u_accum;              // expected-error{{compile with '-enable-fixed-point' to enable fixed point types}}
+unsigned long _Accum u_long_accum;    // expected-error{{compile with '-enable-fixed-point' to enable fixed point types}}
+
+// Aliased fixed point types
+short _Accum short_accum;             // expected-error{{compile with '-enable-fixed-point' to enable fixed point types}}
+_Accum accum;                         // expected-error{{compile with '-enable-fixed-point' to enable fixed point types}}
+                                      // expected-warning@-1{{type specifier missing, defaults to 'int'}}
+long _Accum long_accum;               // expected-error{{compile with '-enable-fixed-point' to enable fixed point types}}
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);