Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10941,13 +10941,9 @@
     }
   }
 
-  // fold (fsub A, (fneg B)) -> (fadd A, B)
-  if (isNegatibleForFree(N1, LegalOperations, TLI, &Options))
-    return DAG.getNode(ISD::FADD, DL, VT, N0,
-                       GetNegatedExpression(N1, DAG, LegalOperations), Flags);
-
   // If 'unsafe math' is enabled, fold lots of things.
-  if (Options.UnsafeFPMath) {
+  if (Options.UnsafeFPMath || 
+      (Flags.hasAllowReassociation() && Flags.hasNoSignedZeros())) {
     // (fsub x, (fadd x, y)) -> (fneg y)
     // (fsub x, (fadd y, x)) -> (fneg y)
     if (N1.getOpcode() == ISD::FADD) {
@@ -10962,6 +10958,11 @@
     }
   }
 
+  // fold (fsub A, (fneg B)) -> (fadd A, B)
+  if (isNegatibleForFree(N1, LegalOperations, TLI, &Options))
+    return DAG.getNode(ISD::FADD, DL, VT, N0,
+                       GetNegatedExpression(N1, DAG, LegalOperations), Flags);
+
   // FSUB -> FMA combines:
   if (SDValue Fused = visitFSUBForFMACombine(N)) {
     AddToWorklist(Fused.getNode());
Index: test/CodeGen/X86/fp-fold.ll
===================================================================
--- test/CodeGen/X86/fp-fold.ll
+++ test/CodeGen/X86/fp-fold.ll
@@ -89,12 +89,10 @@
 }
 
 define float @fsub_neg_y(float %x, float %y) {
-; UNSAFE-LABEL: fsub_neg_y:
-; UNSAFE:       # %bb.0:
-; UNSAFE-NEXT:    mulss {{.*}}(%rip), %xmm0
-; UNSAFE-NEXT:    subss %xmm1, %xmm0
-; UNSAFE-NEXT:    addss %xmm1, %xmm0
-; UNSAFE-NEXT:    retq
+; ANY-LABEL: fsub_neg_y:
+; ANY:       # %bb.0:
+; ANY-NEXT:    mulss {{.*}}(%rip), %xmm0
+; ANY-NEXT:    retq
   %mul = fmul float %x, 5.000000e+00
   %add = fadd float %mul, %y 
   %r = fsub nsz reassoc float %y, %add