Index: lib/CodeGen/MachineCombiner.cpp
===================================================================
--- lib/CodeGen/MachineCombiner.cpp
+++ lib/CodeGen/MachineCombiner.cpp
@@ -242,20 +242,19 @@
   // Get depth, latency and slack of Root.
   unsigned RootDepth = BlockTrace.getInstrCycles(Root).Depth;
   unsigned RootLatency = TSchedModel.computeInstrLatency(Root);
-  unsigned RootSlack = BlockTrace.getInstrSlack(Root);
 
   DEBUG(dbgs() << "DEPENDENCE DATA FOR " << Root << "\n";
         dbgs() << " NewRootDepth: " << NewRootDepth
                << " NewRootLatency: " << NewRootLatency << "\n";
         dbgs() << " RootDepth: " << RootDepth << " RootLatency: " << RootLatency
-               << " RootSlack: " << RootSlack << "\n";
+               << "\n";
         dbgs() << " NewRootDepth + NewRootLatency = "
                << NewRootDepth + NewRootLatency << "\n";
-        dbgs() << " RootDepth + RootLatency + RootSlack = "
-               << RootDepth + RootLatency + RootSlack << "\n";);
+        dbgs() << " RootDepth + RootLatency = "
+               << RootDepth + RootLatency << "\n";);
 
   unsigned NewCycleCount = NewRootDepth + NewRootLatency;
-  unsigned OldCycleCount = RootDepth + RootLatency + RootSlack;
+  unsigned OldCycleCount = RootDepth + RootLatency;
   
   if (NewCodeHasLessInsts)
     return NewCycleCount <= OldCycleCount;
Index: test/CodeGen/X86/machine-combiner.ll
===================================================================
--- test/CodeGen/X86/machine-combiner.ll
+++ test/CodeGen/X86/machine-combiner.ll
@@ -632,10 +632,10 @@
 ; AVX-NEXT:  callq   bar
 ; AVX-NEXT:  vmovsd  %xmm0, (%rsp)
 ; AVX-NEXT:  callq   bar
-; AVX-NEXT:  vmovsd  (%rsp), %xmm1
-; AVX:       vaddsd  8(%rsp), %xmm1, %xmm1
+; AVX-NEXT:  vmovsd  8(%rsp), %xmm1
+; AVX:       vaddsd  16(%rsp), %xmm1, %xmm1
+; AVX-NEXT:  vaddsd  (%rsp), %xmm0, %xmm0
 ; AVX-NEXT:  vaddsd  %xmm0, %xmm1, %xmm0
-; AVX-NEXT:  vaddsd  16(%rsp), %xmm0, %xmm0
 
   %x0 = call double @bar()
   %x1 = call double @bar()
@@ -656,9 +656,10 @@
 ; AVX-NEXT:  callq   bar
 ; AVX-NEXT:  vmovsd  %xmm0, (%rsp)
 ; AVX-NEXT:  callq   bar
+; AVX-NEXT:  vmovsd  8(%rsp), %xmm1
+; AVX:       vaddsd  16(%rsp), %xmm1, %xmm1
 ; AVX-NEXT:  vaddsd  (%rsp), %xmm0, %xmm0
-; AVX-NEXT:  vaddsd  8(%rsp), %xmm0, %xmm0
-; AVX-NEXT:  vaddsd  16(%rsp), %xmm0, %xmm0
+; AVX-NEXT:  vaddsd  %xmm0, %xmm1, %xmm0
 
   %x0 = call double @bar()
   %x1 = call double @bar()