Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10930,13 +10930,8 @@
     }
   }
 
-  // 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()) {
     // (fsub x, (fadd x, y)) -> (fneg y)
     // (fsub x, (fadd y, x)) -> (fneg y)
     if (N1.getOpcode() == ISD::FADD) {
@@ -10951,6 +10946,11 @@
     }
   }
 
+  // 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
@@ -88,6 +88,21 @@
   ret float %r
 }
 
+define float @fsub_neg_y(float %x, float %y) {
+; ANY-LABEL: fsub_neg_y:
+; ANY:       # %bb.0:
+; ANY-NEXT:    mulss %xmm1, %xmm0
+; ANY-NEXT:    andps {{.*}}(%rip), %xmm0
+; ANY-NEXT:    mulss {{.*}}(%rip), %xmm0
+; ANY-NEXT:    retq
+  %mul1 = fmul float %x, %y
+  %abs = call float @llvm.fabs.f32(float %mul1) #1
+  %mul2 = fmul float %abs, 5.000000e+00
+  %add = fadd float %mul2, 1.0
+  %r = fsub reassoc float 1.0, %add 
+  ret float %r
+}
+
 define float @fsub_negzero(float %x) {
 ; STRICT-LABEL: fsub_negzero:
 ; STRICT:       # %bb.0:
@@ -153,3 +168,5 @@
   %r = fmul reassoc float %mul, 4.0
   ret float %r
 }
+
+declare float @llvm.fabs.f32(float) #1