diff --git a/llvm/lib/CodeGen/MachineSink.cpp b/llvm/lib/CodeGen/MachineSink.cpp
--- a/llvm/lib/CodeGen/MachineSink.cpp
+++ b/llvm/lib/CodeGen/MachineSink.cpp
@@ -601,6 +601,49 @@
           FindSuccToSinkTo(MI, SuccToSinkTo, BreakPHIEdge, AllSuccessors))
     return isProfitableToSinkTo(Reg, MI, SuccToSinkTo, MBB2, AllSuccessors);
 
+  // If this instruction is inside a loop and sinking this instruction can make
+  // more registers live range shorten, it is still prifitable.
+  MachineLoop *ML = LI->getLoopFor(MBB);
+  int LiveRangeShortenCount = 0;
+  if (ML) {
+    for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
+      const MachineOperand &MO = MI.getOperand(i);
+      // Ignore non-register operands.
+      if (!MO.isReg())
+        continue;
+      Register Reg = MO.getReg();
+      // Don't handle physical register.
+      if (Reg == 0 || Register::isPhysicalRegister(Reg))
+        return false;
+
+      // Users for the defs are all dominated by SuccToSinkTo.
+      if (MO.isDef()) {
+        // This def register's live range is shortened after sinking.
+        bool LocalUse = false;
+        if (!AllUsesDominatedByBlock(Reg, SuccToSinkTo, MBB, BreakPHIEdge,
+                                     LocalUse))
+          return false;
+        LiveRangeShortenCount++;
+      } else {
+        MachineInstr *DefMI = MRI->getVRegDef(Reg);
+        // DefMI is defined outside of loop. There should be no live range
+        // impact for this operand. Defination outside of loop means: 
+        // 1: defination is outside of loop.
+        // 2: defination is in this loop, but it is a PHI in the loop header.
+        if (LI->getLoopFor(DefMI->getParent()) != ML ||
+            (DefMI->isPHI() && LI->isLoopHeader(DefMI->getParent())))
+          continue;
+        // DefMI is inside the loop.
+        LiveRangeShortenCount--;
+      }
+    }
+    // If there is no live range shorten number degradation, we treat it as
+    // profitable. Because after sinking all users of one defination inside the
+    // loop, we can also sink the defination later.
+    if (LiveRangeShortenCount >= 0)
+      return true;
+  }
+
   // If SuccToSinkTo is final destination and it is a post dominator of current
   // block then it is not profitable to sink MI into SuccToSinkTo block.
   return false;
diff --git a/llvm/test/CodeGen/X86/2007-01-13-StackPtrIndex.ll b/llvm/test/CodeGen/X86/2007-01-13-StackPtrIndex.ll
--- a/llvm/test/CodeGen/X86/2007-01-13-StackPtrIndex.ll
+++ b/llvm/test/CodeGen/X86/2007-01-13-StackPtrIndex.ll
@@ -50,7 +50,7 @@
 ; CHECK-NEXT:    movslq (%r9), %rsi
 ; CHECK-NEXT:    xorl %edi, %edi
 ; CHECK-NEXT:    xorps %xmm0, %xmm0
-; CHECK-NEXT:    movb $1, %r10b
+; CHECK-NEXT:    movb $1, %r9b
 ; CHECK-NEXT:    jmp .LBB0_3
 ; CHECK-NEXT:    .p2align 4, 0x90
 ; CHECK-NEXT:  .LBB0_9: # %b1606
@@ -87,7 +87,7 @@
 ; CHECK-NEXT:    je .LBB0_37
 ; CHECK-NEXT:  .LBB0_18: # %b188
 ; CHECK-NEXT:    # in Loop: Header=BB0_3 Depth=1
-; CHECK-NEXT:    testb %r10b, %r10b
+; CHECK-NEXT:    testb %r9b, %r9b
 ; CHECK-NEXT:    jne .LBB0_4
 ; CHECK-NEXT:    .p2align 4, 0x90
 ; CHECK-NEXT:  .LBB0_19: # %a30b294
@@ -97,27 +97,23 @@
 ; CHECK-NEXT:    je .LBB0_19
 ; CHECK-NEXT:  .LBB0_4: # %a33b
 ; CHECK-NEXT:    # in Loop: Header=BB0_3 Depth=1
-; CHECK-NEXT:    movl %esi, %eax
-; CHECK-NEXT:    orl %r8d, %eax
-; CHECK-NEXT:    movl %eax, %r9d
-; CHECK-NEXT:    shrl $31, %r9d
-; CHECK-NEXT:    testl %eax, %eax
+; CHECK-NEXT:    movl %esi, %r10d
+; CHECK-NEXT:    orl %r8d, %r10d
 ; CHECK-NEXT:    jns .LBB0_20
 ; CHECK-NEXT:  .LBB0_5: # %a50b
 ; CHECK-NEXT:    # in Loop: Header=BB0_3 Depth=1
+; CHECK-NEXT:    shrl $31, %r10d
 ; CHECK-NEXT:    movl %r8d, %eax
 ; CHECK-NEXT:    orl %esi, %eax
-; CHECK-NEXT:    movl %eax, %r11d
-; CHECK-NEXT:    shrl $31, %r11d
-; CHECK-NEXT:    testl %eax, %eax
 ; CHECK-NEXT:    jns .LBB0_26
 ; CHECK-NEXT:  .LBB0_6: # %a57b
 ; CHECK-NEXT:    # in Loop: Header=BB0_3 Depth=1
-; CHECK-NEXT:    testb %r9b, %r9b
+; CHECK-NEXT:    shrl $31, %eax
+; CHECK-NEXT:    testb %r10b, %r10b
 ; CHECK-NEXT:    je .LBB0_30
 ; CHECK-NEXT:  .LBB0_7: # %a66b
 ; CHECK-NEXT:    # in Loop: Header=BB0_3 Depth=1
-; CHECK-NEXT:    testb %r11b, %r11b
+; CHECK-NEXT:    testb %al, %al
 ; CHECK-NEXT:    jne .LBB0_8
 ; CHECK-NEXT:    .p2align 4, 0x90
 ; CHECK-NEXT:  .LBB0_34: # %a74b
@@ -187,7 +183,7 @@
 ; CHECK-NEXT:    je .LBB0_38
 ; CHECK-NEXT:  .LBB0_27: # %b879
 ; CHECK-NEXT:    # in Loop: Header=BB0_26 Depth=2
-; CHECK-NEXT:    testb %r10b, %r10b
+; CHECK-NEXT:    testb %r9b, %r9b
 ; CHECK-NEXT:    jne .LBB0_28
 ; CHECK-NEXT:    .p2align 4, 0x90
 ; CHECK-NEXT:  .LBB0_29: # %a53b1019