Index: cfe/trunk/lib/Basic/Targets.cpp
===================================================================
--- cfe/trunk/lib/Basic/Targets.cpp
+++ cfe/trunk/lib/Basic/Targets.cpp
@@ -8385,6 +8385,97 @@
   }
 };
 
+
+// AVR Target
+class AVRTargetInfo : public TargetInfo {
+public:
+  AVRTargetInfo(const llvm::Triple &Triple, const TargetOptions &)
+      : TargetInfo(Triple) {
+    TLSSupported = false;
+    PointerWidth = 16;
+    PointerAlign = 8;
+    IntWidth = 16;
+    IntAlign = 8;
+    LongWidth = 32;
+    LongAlign = 8;
+    LongLongWidth = 64;
+    LongLongAlign = 8;
+    SuitableAlign = 8;
+    DefaultAlignForAttributeAligned = 8;
+    HalfWidth = 16;
+    HalfAlign = 8;
+    FloatWidth = 32;
+    FloatAlign = 8;
+    DoubleWidth = 32;
+    DoubleAlign = 8;
+    DoubleFormat = &llvm::APFloat::IEEEsingle();
+    LongDoubleWidth = 32;
+    LongDoubleAlign = 8;
+    LongDoubleFormat = &llvm::APFloat::IEEEsingle();
+    SizeType = UnsignedInt;
+    PtrDiffType = SignedInt;
+    IntPtrType = SignedInt;
+    Char16Type = UnsignedInt;
+    WCharType = SignedInt;
+    WIntType = SignedInt;
+    Char32Type = UnsignedLong;
+    SigAtomicType = SignedChar;
+    resetDataLayout("e-p:16:16:16-i8:8:8-i16:16:16-i32:32:32-i64:64:64"
+		    "-f32:32:32-f64:64:64-n8");
+  }
+  void getTargetDefines(const LangOptions &Opts,
+                        MacroBuilder &Builder) const override {
+    Builder.defineMacro("__AVR__");
+  }
+  ArrayRef<Builtin::Info> getTargetBuiltins() const override {
+    return None;
+  }
+  BuiltinVaListKind getBuiltinVaListKind() const override {
+    return TargetInfo::VoidPtrBuiltinVaList;
+  }
+  const char *getClobbers() const override {
+    return "";
+  }
+  ArrayRef<const char *> getGCCRegNames() const override {
+    static const char * const GCCRegNames[] = {
+      "r0",   "r1",   "r2",   "r3",   "r4",   "r5",   "r6",   "r7",
+      "r8",   "r9",   "r10",  "r11",  "r12",  "r13",  "r14",  "r15",
+      "r16",  "r17",  "r18",  "r19",  "r20",  "r21",  "r22",  "r23",
+      "r24",  "r25",  "X",    "Y",    "Z",    "SP"
+    };
+    return llvm::makeArrayRef(GCCRegNames);
+  }
+  ArrayRef<TargetInfo::GCCRegAlias> getGCCRegAliases() const override {
+    return None;
+  }
+  ArrayRef<TargetInfo::AddlRegName> getGCCAddlRegNames() const override {
+    static const TargetInfo::AddlRegName AddlRegNames[] = {
+      { { "r26", "r27"}, 26 },
+      { { "r28", "r29"}, 27 },
+      { { "r30", "r31"}, 28 },
+      { { "SPL", "SPH"}, 29 },
+    };
+    return llvm::makeArrayRef(AddlRegNames);
+  }
+  bool validateAsmConstraint(const char *&Name,
+                             TargetInfo::ConstraintInfo &Info) const override {
+    return false;
+  }
+  IntType getIntTypeByWidth(unsigned BitWidth,
+                            bool IsSigned) const final {
+    // AVR prefers int for 16-bit integers.
+    return BitWidth == 16 ? (IsSigned ? SignedInt : UnsignedInt)
+                          : TargetInfo::getIntTypeByWidth(BitWidth, IsSigned);
+  }
+  IntType getLeastIntTypeByWidth(unsigned BitWidth,
+                                 bool IsSigned) const final {
+    // AVR uses int for int_least16_t and int_fast16_t.
+    return BitWidth == 16
+               ? (IsSigned ? SignedInt : UnsignedInt)
+               : TargetInfo::getLeastIntTypeByWidth(BitWidth, IsSigned);
+  }
+};
+
 } // end anonymous namespace
 
 //===----------------------------------------------------------------------===//
@@ -8507,6 +8598,8 @@
       return new ARMbeTargetInfo(Triple, Opts);
     }
 
+  case llvm::Triple::avr:
+    return new AVRTargetInfo(Triple, Opts);
   case llvm::Triple::bpfeb:
   case llvm::Triple::bpfel:
     return new BPFTargetInfo(Triple, Opts);
Index: cfe/trunk/lib/Driver/Driver.cpp
===================================================================
--- cfe/trunk/lib/Driver/Driver.cpp
+++ cfe/trunk/lib/Driver/Driver.cpp
@@ -3764,6 +3764,9 @@
       case llvm::Triple::wasm64:
         TC = new toolchains::WebAssembly(*this, Target, Args);
         break;
+      case llvm::Triple::avr:
+        TC = new toolchains::AVRToolChain(*this, Target, Args);
+        break;
       default:
         if (Target.getVendor() == llvm::Triple::Myriad)
           TC = new toolchains::MyriadToolChain(*this, Target, Args);
Index: cfe/trunk/lib/Driver/ToolChains.h
===================================================================
--- cfe/trunk/lib/Driver/ToolChains.h
+++ cfe/trunk/lib/Driver/ToolChains.h
@@ -1349,6 +1349,16 @@
   SanitizerMask getSupportedSanitizers() const override;
 };
 
+class LLVM_LIBRARY_VISIBILITY AVRToolChain : public Generic_ELF {
+protected:
+  Tool *buildLinker() const override;
+public:
+  AVRToolChain(const Driver &D, const llvm::Triple &Triple,
+               const llvm::opt::ArgList &Args);
+  bool IsIntegratedAssemblerDefault() const override { return true; }
+};
+
+
 } // end namespace toolchains
 } // end namespace driver
 } // end namespace clang
Index: cfe/trunk/lib/Driver/ToolChains.cpp
===================================================================
--- cfe/trunk/lib/Driver/ToolChains.cpp
+++ cfe/trunk/lib/Driver/ToolChains.cpp
@@ -5318,3 +5318,12 @@
     Res |= SanitizerKind::SafeStack;
   return Res;
 }
+
+/// AVR Toolchain
+AVRToolChain::AVRToolChain(const Driver &D, const llvm::Triple &Triple,
+                           const ArgList &Args)
+  : Generic_ELF(D, Triple, Args) { }
+Tool *AVRToolChain::buildLinker() const {
+  return new tools::AVR::Linker(*this);
+}
+// End AVR
Index: cfe/trunk/lib/Driver/Tools.h
===================================================================
--- cfe/trunk/lib/Driver/Tools.h
+++ cfe/trunk/lib/Driver/Tools.h
@@ -990,6 +990,19 @@
 
 }  // end namespace NVPTX
 
+namespace AVR {
+class LLVM_LIBRARY_VISIBILITY Linker : public GnuTool {
+public:
+  Linker(const ToolChain &TC) : GnuTool("AVR::Linker", "avr-ld", TC) {}
+  bool hasIntegratedCPP() const override { return false; }
+  bool isLinkJob() const override { return true; }
+  void ConstructJob(Compilation &C, const JobAction &JA,
+                    const InputInfo &Output, const InputInfoList &Inputs,
+                    const llvm::opt::ArgList &TCArgs,
+                    const char *LinkingOutput) const override;
+};
+} // end namespace AVR
+
 } // end namespace tools
 } // end namespace driver
 } // end namespace clang
Index: cfe/trunk/lib/Driver/Tools.cpp
===================================================================
--- cfe/trunk/lib/Driver/Tools.cpp
+++ cfe/trunk/lib/Driver/Tools.cpp
@@ -12191,3 +12191,19 @@
   const char *Exec = Args.MakeArgString(TC.GetProgramPath("fatbinary"));
   C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs, Inputs));
 }
+
+void AVR::Linker::ConstructJob(Compilation &C, const JobAction &JA,
+                               const InputInfo &Output,
+                               const InputInfoList &Inputs,
+                               const ArgList &Args,
+                               const char *LinkingOutput) const {
+
+  std::string Linker = getToolChain().GetProgramPath(getShortName());
+  ArgStringList CmdArgs;
+  AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs, JA);
+  CmdArgs.push_back("-o");
+  CmdArgs.push_back(Output.getFilename());
+  C.addCommand(llvm::make_unique<Command>(JA, *this, Args.MakeArgString(Linker),
+                                          CmdArgs, Inputs));
+}
+// AVR tools end.
Index: cfe/trunk/test/Driver/avr-toolchain.c
===================================================================
--- cfe/trunk/test/Driver/avr-toolchain.c
+++ cfe/trunk/test/Driver/avr-toolchain.c
@@ -0,0 +1,4 @@
+// A basic clang -cc1 command-line.
+
+// RUN: %clang %s -### -target avr 2>&1 | FileCheck -check-prefix=CC1 %s
+// CC1: clang{{.*}} "-cc1" "-triple" "avr"
Index: cfe/trunk/test/Preprocessor/init.c
===================================================================
--- cfe/trunk/test/Preprocessor/init.c
+++ cfe/trunk/test/Preprocessor/init.c
@@ -9189,3 +9189,174 @@
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple x86_64-windows-cygnus < /dev/null | FileCheck -match-full-lines -check-prefix CYGWIN-X64 %s
 // CYGWIN-X64: #define __USER_LABEL_PREFIX__
 
+// RUN: %clang_cc1 -E -dM -ffreestanding -triple=avr \
+// RUN:   < /dev/null \
+// RUN:   | FileCheck -match-full-lines -check-prefix=AVR %s
+//
+// AVR:#define __ATOMIC_ACQUIRE 2
+// AVR:#define __ATOMIC_ACQ_REL 4
+// AVR:#define __ATOMIC_CONSUME 1
+// AVR:#define __ATOMIC_RELAXED 0
+// AVR:#define __ATOMIC_RELEASE 3
+// AVR:#define __ATOMIC_SEQ_CST 5
+// AVR:#define __AVR__ 1
+// AVR:#define __BIGGEST_ALIGNMENT__ 1
+// AVR:#define __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__
+// AVR:#define __CHAR16_TYPE__ unsigned int
+// AVR:#define __CHAR32_TYPE__ long unsigned int
+// AVR:#define __CHAR_BIT__ 8
+// AVR:#define __DBL_DECIMAL_DIG__ 9
+// AVR:#define __DBL_DENORM_MIN__ 1.40129846e-45
+// AVR:#define __DBL_DIG__ 6
+// AVR:#define __DBL_EPSILON__ 1.19209290e-7
+// AVR:#define __DBL_HAS_DENORM__ 1
+// AVR:#define __DBL_HAS_INFINITY__ 1
+// AVR:#define __DBL_HAS_QUIET_NAN__ 1
+// AVR:#define __DBL_MANT_DIG__ 24
+// AVR:#define __DBL_MAX_10_EXP__ 38
+// AVR:#define __DBL_MAX_EXP__ 128
+// AVR:#define __DBL_MAX__ 3.40282347e+38
+// AVR:#define __DBL_MIN_10_EXP__ (-37)
+// AVR:#define __DBL_MIN_EXP__ (-125)
+// AVR:#define __DBL_MIN__ 1.17549435e-38
+// AVR:#define __FINITE_MATH_ONLY__ 0
+// AVR:#define __FLT_DECIMAL_DIG__ 9
+// AVR:#define __FLT_DENORM_MIN__ 1.40129846e-45F
+// AVR:#define __FLT_DIG__ 6
+// AVR:#define __FLT_EPSILON__ 1.19209290e-7F
+// AVR:#define __FLT_EVAL_METHOD__ 0
+// AVR:#define __FLT_HAS_DENORM__ 1
+// AVR:#define __FLT_HAS_INFINITY__ 1
+// AVR:#define __FLT_HAS_QUIET_NAN__ 1
+// AVR:#define __FLT_MANT_DIG__ 24
+// AVR:#define __FLT_MAX_10_EXP__ 38
+// AVR:#define __FLT_MAX_EXP__ 128
+// AVR:#define __FLT_MAX__ 3.40282347e+38F
+// AVR:#define __FLT_MIN_10_EXP__ (-37)
+// AVR:#define __FLT_MIN_EXP__ (-125)
+// AVR:#define __FLT_MIN__ 1.17549435e-38F
+// AVR:#define __FLT_RADIX__ 2
+// AVR:#define __GCC_ATOMIC_BOOL_LOCK_FREE 1
+// AVR:#define __GCC_ATOMIC_CHAR16_T_LOCK_FREE 1
+// AVR:#define __GCC_ATOMIC_CHAR32_T_LOCK_FREE 1
+// AVR:#define __GCC_ATOMIC_CHAR_LOCK_FREE 1
+// AVR:#define __GCC_ATOMIC_INT_LOCK_FREE 1
+// AVR:#define __GCC_ATOMIC_LLONG_LOCK_FREE 1
+// AVR:#define __GCC_ATOMIC_LONG_LOCK_FREE 1
+// AVR:#define __GCC_ATOMIC_POINTER_LOCK_FREE 1
+// AVR:#define __GCC_ATOMIC_SHORT_LOCK_FREE 1
+// AVR:#define __GCC_ATOMIC_TEST_AND_SET_TRUEVAL 1
+// AVR:#define __GCC_ATOMIC_WCHAR_T_LOCK_FREE 1
+// AVR:#define __GXX_ABI_VERSION 1002
+// AVR:#define __INT16_C_SUFFIX__ 
+// AVR:#define __INT16_MAX__ 32767
+// AVR:#define __INT16_TYPE__ short
+// AVR:#define __INT32_C_SUFFIX__ L
+// AVR:#define __INT32_MAX__ 2147483647L
+// AVR:#define __INT32_TYPE__ long int
+// AVR:#define __INT64_C_SUFFIX__ LL
+// AVR:#define __INT64_MAX__ 9223372036854775807LL
+// AVR:#define __INT64_TYPE__ long long int
+// AVR:#define __INT8_C_SUFFIX__ 
+// AVR:#define __INT8_MAX__ 127
+// AVR:#define __INT8_TYPE__ signed char
+// AVR:#define __INTMAX_C_SUFFIX__ LL
+// AVR:#define __INTMAX_MAX__ 9223372036854775807LL
+// AVR:#define __INTMAX_TYPE__ long long int
+// AVR:#define __INTPTR_MAX__ 32767
+// AVR:#define __INTPTR_TYPE__ int
+// AVR:#define __INT_FAST16_MAX__ 32767
+// AVR:#define __INT_FAST16_TYPE__ int
+// AVR:#define __INT_FAST32_MAX__ 2147483647L
+// AVR:#define __INT_FAST32_TYPE__ long int
+// AVR:#define __INT_FAST64_MAX__ 9223372036854775807LL
+// AVR:#define __INT_FAST64_TYPE__ long long int
+// AVR:#define __INT_FAST8_MAX__ 127
+// AVR:#define __INT_FAST8_TYPE__ signed char
+// AVR:#define __INT_LEAST16_MAX__ 32767
+// AVR:#define __INT_LEAST16_TYPE__ int
+// AVR:#define __INT_LEAST32_MAX__ 2147483647L
+// AVR:#define __INT_LEAST32_TYPE__ long int
+// AVR:#define __INT_LEAST64_MAX__ 9223372036854775807LL
+// AVR:#define __INT_LEAST64_TYPE__ long long int
+// AVR:#define __INT_LEAST8_MAX__ 127
+// AVR:#define __INT_LEAST8_TYPE__ signed char
+// AVR:#define __INT_MAX__ 32767
+// AVR:#define __LDBL_DECIMAL_DIG__ 9
+// AVR:#define __LDBL_DENORM_MIN__ 1.40129846e-45L
+// AVR:#define __LDBL_DIG__ 6
+// AVR:#define __LDBL_EPSILON__ 1.19209290e-7L
+// AVR:#define __LDBL_HAS_DENORM__ 1
+// AVR:#define __LDBL_HAS_INFINITY__ 1
+// AVR:#define __LDBL_HAS_QUIET_NAN__ 1
+// AVR:#define __LDBL_MANT_DIG__ 24
+// AVR:#define __LDBL_MAX_10_EXP__ 38
+// AVR:#define __LDBL_MAX_EXP__ 128
+// AVR:#define __LDBL_MAX__ 3.40282347e+38L
+// AVR:#define __LDBL_MIN_10_EXP__ (-37)
+// AVR:#define __LDBL_MIN_EXP__ (-125)
+// AVR:#define __LDBL_MIN__ 1.17549435e-38L
+// AVR:#define __LONG_LONG_MAX__ 9223372036854775807LL
+// AVR:#define __LONG_MAX__ 2147483647L
+// AVR:#define __NO_INLINE__ 1
+// AVR:#define __ORDER_BIG_ENDIAN__ 4321
+// AVR:#define __ORDER_LITTLE_ENDIAN__ 1234
+// AVR:#define __ORDER_PDP_ENDIAN__ 3412
+// AVR:#define __PRAGMA_REDEFINE_EXTNAME 1
+// AVR:#define __PTRDIFF_MAX__ 32767
+// AVR:#define __PTRDIFF_TYPE__ int
+// AVR:#define __SCHAR_MAX__ 127
+// AVR:#define __SHRT_MAX__ 32767
+// AVR:#define __SIG_ATOMIC_MAX__ 127
+// AVR:#define __SIG_ATOMIC_WIDTH__ 8
+// AVR:#define __SIZEOF_DOUBLE__ 4
+// AVR:#define __SIZEOF_FLOAT__ 4
+// AVR:#define __SIZEOF_INT__ 2
+// AVR:#define __SIZEOF_LONG_DOUBLE__ 4
+// AVR:#define __SIZEOF_LONG_LONG__ 8
+// AVR:#define __SIZEOF_LONG__ 4
+// AVR:#define __SIZEOF_POINTER__ 2
+// AVR:#define __SIZEOF_PTRDIFF_T__ 2
+// AVR:#define __SIZEOF_SHORT__ 2
+// AVR:#define __SIZEOF_SIZE_T__ 2
+// AVR:#define __SIZEOF_WCHAR_T__ 2
+// AVR:#define __SIZEOF_WINT_T__ 2
+// AVR:#define __SIZE_MAX__ 65535U
+// AVR:#define __SIZE_TYPE__ unsigned int
+// AVR:#define __STDC__ 1
+// AVR:#define __UINT16_MAX__ 65535U
+// AVR:#define __UINT16_TYPE__ unsigned short
+// AVR:#define __UINT32_C_SUFFIX__ UL
+// AVR:#define __UINT32_MAX__ 4294967295UL
+// AVR:#define __UINT32_TYPE__ long unsigned int
+// AVR:#define __UINT64_C_SUFFIX__ ULL
+// AVR:#define __UINT64_MAX__ 18446744073709551615ULL
+// AVR:#define __UINT64_TYPE__ long long unsigned int
+// AVR:#define __UINT8_C_SUFFIX__ 
+// AVR:#define __UINT8_MAX__ 255
+// AVR:#define __UINT8_TYPE__ unsigned char
+// AVR:#define __UINTMAX_C_SUFFIX__ ULL
+// AVR:#define __UINTMAX_MAX__ 18446744073709551615ULL
+// AVR:#define __UINTMAX_TYPE__ long long unsigned int
+// AVR:#define __UINTPTR_MAX__ 65535U
+// AVR:#define __UINTPTR_TYPE__ unsigned int
+// AVR:#define __UINT_FAST16_MAX__ 65535U
+// AVR:#define __UINT_FAST16_TYPE__ unsigned int
+// AVR:#define __UINT_FAST32_MAX__ 4294967295UL
+// AVR:#define __UINT_FAST32_TYPE__ long unsigned int
+// AVR:#define __UINT_FAST64_MAX__ 18446744073709551615ULL
+// AVR:#define __UINT_FAST64_TYPE__ long long unsigned int
+// AVR:#define __UINT_FAST8_MAX__ 255
+// AVR:#define __UINT_FAST8_TYPE__ unsigned char
+// AVR:#define __UINT_LEAST16_MAX__ 65535U
+// AVR:#define __UINT_LEAST16_TYPE__ unsigned int
+// AVR:#define __UINT_LEAST32_MAX__ 4294967295UL
+// AVR:#define __UINT_LEAST32_TYPE__ long unsigned int
+// AVR:#define __UINT_LEAST64_MAX__ 18446744073709551615ULL
+// AVR:#define __UINT_LEAST64_TYPE__ long long unsigned int
+// AVR:#define __UINT_LEAST8_MAX__ 255
+// AVR:#define __UINT_LEAST8_TYPE__ unsigned char
+// AVR:#define __USER_LABEL_PREFIX__ 
+// AVR:#define __WCHAR_MAX__ 32767
+// AVR:#define __WCHAR_TYPE__ int
+// AVR:#define __WINT_TYPE__ int