diff --git a/llvm/lib/Target/AVR/AVR.td b/llvm/lib/Target/AVR/AVR.td
diff --git a/llvm/lib/Target/AVR/AVRRegisterInfo.td b/llvm/lib/Target/AVR/AVRRegisterInfo.td
@@ -0,0 +1,216 @@
+//===-- AVRRegisterInfo.td - AVR Register defs -------------*- tablegen -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+//  Declarations that describe the AVR register file
+//===----------------------------------------------------------------------===//
+
+// 8-bit General purpose register definition.
+class AVRReg<bits<16> num,
+             string name,
+             list<Register> subregs = [],
+             list<string> altNames = []>
+  : RegisterWithSubRegs<name, subregs>
+{
+  field bits<16> Num = num;
+
+  let HWEncoding = num;
+  let Namespace = "AVR";
+  let SubRegs = subregs;
+  let AltNames = altNames;
+}
+
+// Subregister indices.
+let Namespace = "AVR" in
+{
+  def sub_lo : SubRegIndex<8>;
+  def sub_hi : SubRegIndex<8, 8>;
+}
+
+let Namespace = "AVR" in {
+  def ptr : RegAltNameIndex;
+}
+
+
+//===----------------------------------------------------------------------===//
+//  8-bit general purpose registers
+//===----------------------------------------------------------------------===//
+
+def R0  : AVRReg<0,  "r0">,  DwarfRegNum<[0]>;
+def R1  : AVRReg<1,  "r1">,  DwarfRegNum<[1]>;
+def R2  : AVRReg<2,  "r2">,  DwarfRegNum<[2]>;
+def R3  : AVRReg<3,  "r3">,  DwarfRegNum<[3]>;
+def R4  : AVRReg<4,  "r4">,  DwarfRegNum<[4]>;
+def R5  : AVRReg<5,  "r5">,  DwarfRegNum<[5]>;
+def R6  : AVRReg<6,  "r6">,  DwarfRegNum<[6]>;
+def R7  : AVRReg<7,  "r7">,  DwarfRegNum<[7]>;
+def R8  : AVRReg<8,  "r8">,  DwarfRegNum<[8]>;
+def R9  : AVRReg<9,  "r9">,  DwarfRegNum<[9]>;
+def R10 : AVRReg<10, "r10">, DwarfRegNum<[10]>;
+def R11 : AVRReg<11, "r11">, DwarfRegNum<[11]>;
+def R12 : AVRReg<12, "r12">, DwarfRegNum<[12]>;
+def R13 : AVRReg<13, "r13">, DwarfRegNum<[13]>;
+def R14 : AVRReg<14, "r14">, DwarfRegNum<[14]>;
+def R15 : AVRReg<15, "r15">, DwarfRegNum<[15]>;
+def R16 : AVRReg<16, "r16">, DwarfRegNum<[16]>;
+def R17 : AVRReg<17, "r17">, DwarfRegNum<[17]>;
+def R18 : AVRReg<18, "r18">, DwarfRegNum<[18]>;
+def R19 : AVRReg<19, "r19">, DwarfRegNum<[19]>;
+def R20 : AVRReg<20, "r20">, DwarfRegNum<[20]>;
+def R21 : AVRReg<21, "r21">, DwarfRegNum<[21]>;
+def R22 : AVRReg<22, "r22">, DwarfRegNum<[22]>;
+def R23 : AVRReg<23, "r23">, DwarfRegNum<[23]>;
+def R24 : AVRReg<24, "r24">, DwarfRegNum<[24]>;
+def R25 : AVRReg<25, "r25">, DwarfRegNum<[25]>;
+def R26 : AVRReg<26, "r26">, DwarfRegNum<[26]>;
+def R27 : AVRReg<27, "r27">, DwarfRegNum<[27]>;
+def R28 : AVRReg<28, "r28">, DwarfRegNum<[28]>;
+def R29 : AVRReg<29, "r29">, DwarfRegNum<[29]>;
+def R30 : AVRReg<30, "r30">, DwarfRegNum<[30]>;
+def R31 : AVRReg<31, "r31">, DwarfRegNum<[31]>;
+def SPL : AVRReg<32, "SPL">, DwarfRegNum<[32]>;
+def SPH : AVRReg<33, "SPH">, DwarfRegNum<[33]>;
+
+let SubRegIndices = [sub_lo, sub_hi],
+CoveredBySubRegs = 1 in
+{
+  // 16 bit GPR pairs.
+  def SP     : AVRReg<32, "SP",      [SPL, SPH]>, DwarfRegNum<[32]>;
+
+  // The pointer registers (X,Y,Z) are a special case because they
+  // are printed as a `high:low` pair when a DREG is expected,
+  // but printed using `X`, `Y`, `Z` when a pointer register is expected.
+  let RegAltNameIndices = [ptr] in {
+      def R31R30 : AVRReg<30, "r31:r30", [R30, R31], ["Z"]>, DwarfRegNum<[30]>;
+      def R29R28 : AVRReg<28, "r29:r28", [R28, R29], ["Y"]>, DwarfRegNum<[28]>;
+      def R27R26 : AVRReg<26, "r27:r26", [R26, R27], ["X"]>, DwarfRegNum<[26]>;
+  }
+  def R25R24 : AVRReg<24, "r25:r24", [R24, R25]>, DwarfRegNum<[24]>;
+  def R23R22 : AVRReg<22, "r23:r22", [R22, R23]>, DwarfRegNum<[22]>;
+  def R21R20 : AVRReg<20, "r21:r20", [R20, R21]>, DwarfRegNum<[20]>;
+  def R19R18 : AVRReg<18, "r19:r18", [R18, R19]>, DwarfRegNum<[18]>;
+  def R17R16 : AVRReg<16, "r17:r16", [R16, R17]>, DwarfRegNum<[16]>;
+  def R15R14 : AVRReg<14, "r15:r14", [R14, R15]>, DwarfRegNum<[14]>;
+  def R13R12 : AVRReg<12, "r13:r12", [R12, R13]>, DwarfRegNum<[12]>;
+  def R11R10 : AVRReg<10, "r11:r10", [R10, R11]>, DwarfRegNum<[10]>;
+  def R9R8   : AVRReg<8,  "r9:r8",   [R8, R9]>,   DwarfRegNum<[8]>;
+  def R7R6   : AVRReg<6,  "r7:r6",   [R6, R7]>,   DwarfRegNum<[6]>;
+  def R5R4   : AVRReg<4,  "r5:r4",   [R4, R5]>,   DwarfRegNum<[4]>;
+  def R3R2   : AVRReg<2,  "r3:r2",   [R2, R3]>,   DwarfRegNum<[2]>;
+  def R1R0   : AVRReg<0,  "r1:r0",   [R0, R1]>,   DwarfRegNum<[0]>;
+}
+
+//===----------------------------------------------------------------------===//
+// Register Classes
+//===----------------------------------------------------------------------===//
+
+//:TODO: use proper set instructions instead of using always "add"
+
+// Main 8-bit register class.
+def GPR8 : RegisterClass<"AVR", [i8], 8,
+  (
+    // Return value and argument registers.
+    add R24, R25, R18, R19, R20, R21, R22, R23,
+    // Scratch registers.
+    R30, R31, R26, R27,
+    // Callee saved registers.
+    R28, R29, R17, R16, R15, R14, R13, R12, R11, R10,
+    R9, R8, R7, R6, R5, R4, R3, R2, R0, R1
+  )>;
+
+// Simple lower registers r0..r15
+def GPR8lo : RegisterClass<"AVR", [i8], 8,
+  (
+    add R15, R14, R13, R12, R11, R10, R9, R8, R7, R6, R5, R4, R3, R2, R0, R1
+  )>;
+
+// 8-bit register class for instructions which take immediates.
+def LD8 : RegisterClass<"AVR", [i8], 8,
+  (
+    // Return value and arguments.
+    add R24, R25, R18, R19, R20, R21, R22, R23,
+    // Scratch registers.
+    R30, R31, R26, R27,
+    // Callee saved registers.
+    R28, R29, R17, R16
+  )>;
+
+// Simple lower registers r16..r23
+def LD8lo : RegisterClass<"AVR", [i8], 8,
+  (
+    add R23, R22, R21, R20, R19, R18, R17, R16
+  )>;
+
+// Main 16-bit pair register class.
+def DREGS : RegisterClass<"AVR", [i16], 8,
+  (
+    // Return value and arguments.
+    add R25R24, R19R18, R21R20, R23R22,
+    // Scratch registers.
+    R31R30, R27R26,
+    // Callee saved registers.
+    R29R28, R17R16, R15R14, R13R12, R11R10,
+    R9R8, R7R6, R5R4, R3R2, R1R0
+  )>;
+
+// 16-bit register class for immediate instructions.
+def DLDREGS : RegisterClass<"AVR", [i16], 8,
+  (
+    // Return value and arguments.
+    add R25R24, R19R18, R21R20, R23R22,
+    // Scratch registers.
+    R31R30, R27R26,
+    // Callee saved registers.
+    R29R28, R17R16
+  )>;
+
+// 16-bit register class for the adiw/sbiw instructions.
+def IWREGS : RegisterClass<"AVR", [i16], 8,
+  (
+    // Return value and arguments.
+    add R25R24,
+    // Scratch registers.
+    R31R30, R27R26,
+    // Callee saved registers.
+    R29R28
+  )>;
+
+// 16-bit register class for the ld and st instructions.
+// AKA X,Y, and Z
+def PTRREGS : RegisterClass<"AVR", [i16], 8,
+  (
+    add R27R26, // X
+        R29R28, // Y
+        R31R30  // Z
+  ), ptr>;
+
+// 16-bit register class for the ldd and std instructions.
+// AKA Y and Z.
+def PTRDISPREGS : RegisterClass<"AVR", [i16], 8,
+  (
+    add R31R30, R29R28
+  ), ptr>;
+
+// We have a bunch of instructions with an explicit Z register argument. We
+// model this using a register class containing only the Z register.
+// :TODO: Rename to 'ZREG'.
+def ZREGS : RegisterClass<"AVR", [i16], 8, (add R31R30)>;
+
+// Register class used for the stack read pseudo instruction.
+def GPRSP: RegisterClass<"AVR", [i16], 8, (add SP)>;
+
+//:TODO: if we remove this we get an error in tablegen
+//:TODO: this is just a hack, remove it once add16 works!
+// Status register.
+def SREG : AVRReg<14, "FLAGS">, DwarfRegNum<[88]>;
+def CCR : RegisterClass<"AVR", [i8], 8, (add SREG)>
+{
+  let CopyCost = -1;      // Don't allow copying of status registers
+}
+
diff --git a/llvm/lib/Target/AVR/CMakeLists.txt b/llvm/lib/Target/AVR/CMakeLists.txt
@@ -1,4 +1,7 @@
+set(LLVM_TARGET_DEFINITIONS AVR.td)
 
+tablegen(LLVM AVRGenRegisterInfo.inc -gen-register-info)
+add_public_tablegen_target(AVRCommonTableGen)
 
 add_llvm_target(AVRCodeGen
     AVRTargetMachine.cpp

diff --git a/llvm/lib/Target/AVR/Makefile b/llvm/lib/Target/AVR/Makefile
@@ -12,7 +12,7 @@ LIBRARYNAME = LLVMAVRCodeGen
 TARGET = AVR
 
 # Make sure that tblgen is run, first thing.
-BUILT_SOURCES =
+BUILT_SOURCES = AVRGenRegisterInfo.inc
 
 DIRS = TargetInfo