diff --git a/lib/Target/X86/CMakeLists.txt b/lib/Target/X86/CMakeLists.txt
index 95f1f22..d14899d 100644
--- a/lib/Target/X86/CMakeLists.txt
+++ b/lib/Target/X86/CMakeLists.txt
@@ -25,6 +25,7 @@
   X86JITInfo.cpp
   X86MCInstLower.cpp
   X86MachineFunctionInfo.cpp
+  X86PadShortFunction.cpp
   X86RegisterInfo.cpp
   X86SelectionDAGInfo.cpp
   X86Subtarget.cpp
diff --git a/lib/Target/X86/X86.h b/lib/Target/X86/X86.h
index 2bff7ab..1f9919f 100644
--- a/lib/Target/X86/X86.h
+++ b/lib/Target/X86/X86.h
@@ -66,6 +66,10 @@
 /// \brief Creates an X86-specific Target Transformation Info pass.
 ImmutablePass *createX86TargetTransformInfoPass(const X86TargetMachine *TM);
 
+/// createX86PadShortFunctions - Return a pass that pads short functions
+/// with NOOPs. This will prevent a stall when returning on the Atom.
+FunctionPass *createX86PadShortFunctions();
+
 } // End llvm namespace
 
 #endif
diff --git a/lib/Target/X86/X86.td b/lib/Target/X86/X86.td
index b9d8cf7..3ab2899 100644
--- a/lib/Target/X86/X86.td
+++ b/lib/Target/X86/X86.td
@@ -123,8 +123,11 @@
 def FeatureLeaForSP : SubtargetFeature<"lea-sp", "UseLeaForSP", "true",
                                      "Use LEA for adjusting the stack pointer">;
 def FeatureSlowDivide : SubtargetFeature<"idiv-to-divb",
-                          "HasSlowDivide", "true",
-                          "Use small divide for positive values less than 256">;
+                                     "HasSlowDivide", "true",
+                                     "Use small divide for positive values less than 256">;
+def FeaturePadShortFunctions : SubtargetFeature<"pad-short-functions",
+                                     "PadShortFunctions", "true",
+                                     "Pad short functions">;
 
 //===----------------------------------------------------------------------===//
 // X86 processors supported.
@@ -167,7 +170,7 @@
                                FeatureSlowBTMem]>;
 def : AtomProc<"atom",        [ProcIntelAtom, FeatureSSSE3, FeatureCMPXCHG16B,
                                FeatureMOVBE, FeatureSlowBTMem, FeatureLeaForSP,
-                               FeatureSlowDivide]>;
+                               FeatureSlowDivide, FeaturePadShortFunctions]>;
 // "Arrandale" along with corei3 and corei5
 def : Proc<"corei7",          [FeatureSSE42, FeatureCMPXCHG16B,
                                FeatureSlowBTMem, FeatureFastUAMem,
diff --git a/lib/Target/X86/X86PadShortFunction.cpp b/lib/Target/X86/X86PadShortFunction.cpp
new file mode 100644
index 0000000..c22872f
--- /dev/null
+++ b/lib/Target/X86/X86PadShortFunction.cpp
@@ -0,0 +1,171 @@
+//===-------- X86PadShortFunction.cpp - pad short functions -----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the pass which will pad short functions to prevent
+// a stall if a function returns before the return address is ready. This
+// is needed for some Intel Atom processors.
+//
+//===----------------------------------------------------------------------===//
+
+#include <algorithm>
+
+#define DEBUG_TYPE "x86-pad-short-functions"
+#include "X86.h"
+#include "X86InstrInfo.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetInstrInfo.h"
+
+using namespace llvm;
+
+STATISTIC(NumBBsPadded, "Number of basic blocks padded");
+
+namespace {
+  struct PadShortFunc : public MachineFunctionPass {
+    static char ID;
+    PadShortFunc() : MachineFunctionPass(ID)
+                   , Threshold(4), TM(0), TII(0) {}
+
+    virtual bool runOnMachineFunction(MachineFunction &MF);
+
+    virtual const char *getPassName() const {
+      return "X86 Atom pad short functions";
+    }
+
+  private:
+    void findReturns(MachineBasicBlock *MBB,
+                     unsigned int Cycles = 0);
+
+    bool cyclesUntilReturn(MachineBasicBlock *MBB,
+                           unsigned int &Cycles,
+                           MachineBasicBlock::iterator *Location = 0);
+
+    void addPadding(MachineBasicBlock *MBB,
+                    MachineBasicBlock::iterator &MBBI,
+                    unsigned int NOOPsToAdd);
+
+    const unsigned int Threshold;
+    DenseMap<MachineBasicBlock*, unsigned int> ReturnBBs;
+
+    const TargetMachine *TM;
+    const TargetInstrInfo *TII;
+  };
+
+  char PadShortFunc::ID = 0;
+}
+
+FunctionPass *llvm::createX86PadShortFunctions() {
+  return new PadShortFunc();
+}
+
+/// runOnMachineFunction - Loop over all of the basic blocks, inserting
+/// NOOP instructions before early exits.
+bool PadShortFunc::runOnMachineFunction(MachineFunction &MF) {
+  bool OptForSize = MF.getFunction()->getAttributes().
+    hasAttribute(AttributeSet::FunctionIndex, Attribute::OptimizeForSize);
+
+  if (OptForSize)
+    return false;
+
+  TM = &MF.getTarget();
+  TII = TM->getInstrInfo();
+
+  // Search through basic blocks and mark the ones that have early returns
+  ReturnBBs.clear();
+  findReturns(MF.begin());
+
+  bool MadeChange = false;
+
+  MachineBasicBlock::iterator ReturnLoc;
+  MachineBasicBlock *MBB;
+  unsigned int Cycles = 0;
+  unsigned int BBCycles;
+
+  // Pad the identified basic blocks with NOOPs
+  for (DenseMap<MachineBasicBlock*, unsigned int>::iterator I = ReturnBBs.begin();
+       I != ReturnBBs.end(); ++I) {
+    MBB = I->first;
+    Cycles = I->second;
+
+    if (Cycles < Threshold) {
+      if (!cyclesUntilReturn(MBB, BBCycles, &ReturnLoc))
+        continue;
+
+      addPadding(MBB, ReturnLoc, Threshold - Cycles);
+      NumBBsPadded++;
+      MadeChange = true;
+    }
+  }
+
+  return MadeChange;
+}
+
+/// findReturn - Starting at MBB, follow control flow and add all
+/// basic blocks that contain a return to ReturnBBs.
+void PadShortFunc::findReturns(MachineBasicBlock *MBB, unsigned int Cycles) {
+  // If this BB has a return, note how many cycles it takes to get there.
+  bool hasReturn = cyclesUntilReturn(MBB, Cycles);
+  if (Cycles >= Threshold)
+    return;
+
+  if (hasReturn) {
+    ReturnBBs[MBB] = std::max(ReturnBBs[MBB], Cycles);
+    return;
+  }
+
+  // Follow branches in BB and look for returns
+  for (MachineBasicBlock::succ_iterator I = MBB->succ_begin();
+      I != MBB->succ_end(); ++I) {
+    findReturns(*I, Cycles);
+  }
+}
+
+/// cyclesUntilReturn - if the MBB has a return instruction, set Location
+/// to the instruction and return true. Return false otherwise.
+/// Cycles will be incremented by the number of cycles taken to reach the
+/// return or the end of the BB, whichever occurs first.
+bool PadShortFunc::cyclesUntilReturn(MachineBasicBlock *MBB,
+                                     unsigned int &Cycles,
+                                     MachineBasicBlock::iterator *Location) {
+  for (MachineBasicBlock::iterator MBBI = MBB->begin();
+        MBBI != MBB->end(); ++MBBI) {
+    MachineInstr *MI = MBBI;
+    // Mark basic blocks with a return instruction. Calls to other
+    // functions do not count because the called function will be padded,
+    // if necessary.
+    if (MI->isReturn() && !MI->isCall()) {
+      if (Location)
+        *Location = MBBI;
+      return true;
+    }
+
+    Cycles += TII->getInstrLatency(TM->getInstrItineraryData(), MI);
+  }
+
+  return false;
+}
+
+/// addPadding - Add the given number of NOOP instructions to the function
+/// just prior to the return at MBBI
+void PadShortFunc::addPadding(MachineBasicBlock *MBB,
+                              MachineBasicBlock::iterator &MBBI,
+                              unsigned int NOOPsToAdd) {
+  DebugLoc DL = MBBI->getDebugLoc();
+
+  while (NOOPsToAdd-- > 0) {
+    BuildMI(*MBB, MBBI, DL, TII->get(X86::NOOP));
+    BuildMI(*MBB, MBBI, DL, TII->get(X86::NOOP));
+  }
+}
diff --git a/lib/Target/X86/X86Subtarget.cpp b/lib/Target/X86/X86Subtarget.cpp
index d493b78..53c28f4 100644
--- a/lib/Target/X86/X86Subtarget.cpp
+++ b/lib/Target/X86/X86Subtarget.cpp
@@ -350,6 +350,7 @@
   , UseLeaForSP(false)
   , HasSlowDivide(false)
   , PostRAScheduler(false)
+  , PadShortFunctions(false)
   , stackAlignment(4)
   // FIXME: this is a known good value for Yonah. How about others?
   , MaxInlineSizeThreshold(128)
diff --git a/lib/Target/X86/X86Subtarget.h b/lib/Target/X86/X86Subtarget.h
index 44f38a1..080f4cf 100644
--- a/lib/Target/X86/X86Subtarget.h
+++ b/lib/Target/X86/X86Subtarget.h
@@ -146,6 +146,10 @@
   /// PostRAScheduler - True if using post-register-allocation scheduler.
   bool PostRAScheduler;
 
+  /// PadShortFunctions - True if the short functions should be padded to prevent
+  /// a stall when returning too early.
+  bool PadShortFunctions;
+
   /// stackAlignment - The minimum alignment known to hold of the stack frame on
   /// entry to the function and which must be maintained by every function.
   unsigned stackAlignment;
@@ -231,6 +235,7 @@
   bool hasCmpxchg16b() const { return HasCmpxchg16b; }
   bool useLeaForSP() const { return UseLeaForSP; }
   bool hasSlowDivide() const { return HasSlowDivide; }
+  bool padShortFunctions() const { return PadShortFunctions; }
 
   bool isAtom() const { return X86ProcFamily == IntelAtom; }
 
diff --git a/lib/Target/X86/X86TargetMachine.cpp b/lib/Target/X86/X86TargetMachine.cpp
index 847e06b..706e64a 100644
--- a/lib/Target/X86/X86TargetMachine.cpp
+++ b/lib/Target/X86/X86TargetMachine.cpp
@@ -202,6 +202,12 @@
     ShouldPrint = true;
   }
 
+  if (getOptLevel() != CodeGenOpt::None &&
+      getX86Subtarget().padShortFunctions()) {
+    addPass(createX86PadShortFunctions());
+    ShouldPrint = true;
+  }
+
   return ShouldPrint;
 }
 
diff --git a/test/CodeGen/X86/atom-pad-short-functions.ll b/test/CodeGen/X86/atom-pad-short-functions.ll
new file mode 100644
index 0000000..54af17d
--- /dev/null
+++ b/test/CodeGen/X86/atom-pad-short-functions.ll
@@ -0,0 +1,78 @@
+; RUN: llc < %s -O1 -mcpu=atom -mtriple=i686-linux  | FileCheck %s
+
+declare void @external_function(...)
+
+define i32 @test_return_val(i32 %a) nounwind {
+; CHECK: test_return_val
+; CHECK: movl
+; CHECK: nop
+; CHECK: nop
+; CHECK: nop
+; CHECK: nop
+; CHECK: nop
+; CHECK: nop
+; CHECK: ret
+  ret i32 %a
+}
+
+define i32 @test_optsize(i32 %a) nounwind optsize {
+; CHECK: test_optsize
+; CHECK: movl
+; CHECK-NEXT: ret
+  ret i32 %a
+}
+
+define i32 @test_add(i32 %a, i32 %b) nounwind {
+; CHECK: test_add
+; CHECK: addl
+; CHECK: nop
+; CHECK: nop
+; CHECK: nop
+; CHECK: nop
+; CHECK: ret
+  %result = add i32 %a, %b
+  ret i32 %result
+}
+
+define i32 @test_multiple_ret(i32 %a, i32 %b, i1 %c) nounwind {
+; CHECK: @test_multiple_ret
+; CHECK: je
+
+; CHECK: nop
+; CHECK: nop
+; CHECK: ret
+
+; CHECK: nop
+; CHECK: nop
+; CHECK: ret
+
+  br i1 %c, label %bb1, label %bb2
+
+bb1:
+  ret i32 %a
+
+bb2:
+  ret i32 %b
+}
+
+define void @test_call_others(i32 %x) nounwind
+{
+; CHECK: test_call_others
+; CHECK: je
+  %tobool = icmp eq i32 %x, 0
+  br i1 %tobool, label %if.end, label %true.case
+
+; CHECK: jmp external_function
+true.case:
+  tail call void bitcast (void (...)* @external_function to void ()*)() nounwind
+  br label %if.end
+
+; CHECK: nop
+; CHECK: nop
+; CHECK: nop
+; CHECK: nop
+; CHECK: ret
+if.end:
+  ret void
+
+}
diff --git a/test/CodeGen/X86/fast-isel-x86-64.ll b/test/CodeGen/X86/fast-isel-x86-64.ll
index cdfaf7f..ad1520e 100644
--- a/test/CodeGen/X86/fast-isel-x86-64.ll
+++ b/test/CodeGen/X86/fast-isel-x86-64.ll
@@ -1,5 +1,5 @@
-; RUN: llc < %s -mattr=-avx -fast-isel -O0 -regalloc=fast -asm-verbose=0 -fast-isel-abort | FileCheck %s
-; RUN: llc < %s -mattr=+avx -fast-isel -O0 -regalloc=fast -asm-verbose=0 -fast-isel-abort | FileCheck %s --check-prefix=AVX
+; RUN: llc < %s -mattr=-avx -fast-isel -mcpu=core2 -O0 -regalloc=fast -asm-verbose=0 -fast-isel-abort | FileCheck %s
+; RUN: llc < %s -mattr=+avx -fast-isel -mcpu=core2 -O0 -regalloc=fast -asm-verbose=0 -fast-isel-abort | FileCheck %s --check-prefix=AVX
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
 target triple = "x86_64-apple-darwin10.0.0"
diff --git a/test/CodeGen/X86/ret-mmx.ll b/test/CodeGen/X86/ret-mmx.ll
index 865e147..778e472 100644
--- a/test/CodeGen/X86/ret-mmx.ll
+++ b/test/CodeGen/X86/ret-mmx.ll
@@ -1,4 +1,4 @@
-; RUN: llc < %s -mtriple=x86_64-apple-darwin11 -mattr=+mmx,+sse2 | FileCheck %s
+; RUN: llc < %s -mtriple=x86_64-apple-darwin11 -mcpu=core2 -mattr=+mmx,+sse2 | FileCheck %s
 ; rdar://6602459
 
 @g_v1di = external global <1 x i64>
diff --git a/test/CodeGen/X86/select.ll b/test/CodeGen/X86/select.ll
index 3bec3ac..09ca07b 100644
--- a/test/CodeGen/X86/select.ll
+++ b/test/CodeGen/X86/select.ll
@@ -282,7 +282,7 @@
 ; ATOM: test13:
 ; ATOM: cmpl
 ; ATOM-NEXT: sbbl
-; ATOM-NEXT: ret
+; ATOM: ret
 }
 
 define i32 @test14(i32 %a, i32 %b) nounwind {
@@ -299,7 +299,7 @@
 ; ATOM: cmpl
 ; ATOM-NEXT: sbbl
 ; ATOM-NEXT: notl
-; ATOM-NEXT: ret
+; ATOM: ret
 }
 
 ; rdar://10961709