diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 9309cf4..3708b1c 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetSubtarget.h"
 #include "llvm/Target/TargetData.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/MRegisterInfo.h"
@@ -21,6 +22,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Target/TargetAsmInfo.h"
+#include "llvm/CallingConv.h"
 using namespace llvm;
 
 /// InitLibcallNames - Set default libcall names.
@@ -194,6 +196,59 @@
 
 TargetLowering::~TargetLowering() {}
 
+
+SDOperand TargetLowering::LowerMEMCPY(SDOperand Op, SelectionDAG &DAG) {
+  assert(getSubtarget() && "Subtarget not defined");
+  SDOperand ChainOp = Op.getOperand(0);
+  SDOperand DestOp = Op.getOperand(1);
+  SDOperand SourceOp = Op.getOperand(2);
+  SDOperand CountOp = Op.getOperand(3);
+  SDOperand AlignOp = Op.getOperand(4);
+  SDOperand AlwaysInlineOp = Op.getOperand(5);
+
+  bool AlwaysInline = (bool)cast<ConstantSDNode>(AlwaysInlineOp)->getValue();
+  unsigned Align = (unsigned)cast<ConstantSDNode>(AlignOp)->getValue();
+  if (Align == 0) Align = 1;
+
+  // If size is unknown, call memcpy.
+  ConstantSDNode *I = dyn_cast<ConstantSDNode>(CountOp);
+  if (!I) {
+    assert(!AlwaysInline && "Cannot inline copy of unknown size");
+    return LowerMEMCPYCall(ChainOp, DestOp, SourceOp, CountOp, DAG);
+  }
+
+  // If not DWORD aligned or if size is more than threshold, then call memcpy.
+  // The libc version is likely to be faster for the following cases. It can
+  // use the address value and run time information about the CPU.
+  // With glibc 2.6.1 on a core 2, coping an array of 100M longs was 30% faster
+  unsigned Size = I->getValue();
+  if (AlwaysInline ||
+      (Size <= getSubtarget()->getMaxInlineSizeThreshold() &&
+       (Align & 3) == 0))
+    return LowerMEMCPYInline(ChainOp, DestOp, SourceOp, Size, Align, DAG);
+  return LowerMEMCPYCall(ChainOp, DestOp, SourceOp, CountOp, DAG);
+}
+
+
+SDOperand TargetLowering::LowerMEMCPYCall(SDOperand Chain,
+                                          SDOperand Dest,
+                                          SDOperand Source,
+                                          SDOperand Count,
+                                          SelectionDAG &DAG) {
+  MVT::ValueType IntPtr = getPointerTy();
+  TargetLowering::ArgListTy Args;
+  TargetLowering::ArgListEntry Entry;
+  Entry.Ty = getTargetData()->getIntPtrType();
+  Entry.Node = Dest; Args.push_back(Entry);
+  Entry.Node = Source; Args.push_back(Entry);
+  Entry.Node = Count; Args.push_back(Entry);
+  std::pair<SDOperand,SDOperand> CallResult =
+      LowerCallTo(Chain, Type::VoidTy, false, false, CallingConv::C, false,
+                  DAG.getExternalSymbol("memcpy", IntPtr), Args, DAG);
+  return CallResult.second;
+}
+
+
 /// computeRegisterProperties - Once all of the register classes are added,
 /// this allows us to compute derived properties we expose.
 void TargetLowering::computeRegisterProperties() {