Index: llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -2132,6 +2132,12 @@
   if (match(&I, m_FNeg(m_OneUse(m_FDiv(m_Constant(C), m_Value(X))))))
     return BinaryOperator::CreateFDivFMF(ConstantExpr::getFNeg(C), X, &I);
 
+  // With NSZ [ counter-example with -0.0: -(-0.0 + 0.0) != 0.0 + -0.0 ]:
+  // -(X + C) --> -X + -C --> -C - X
+  if (I.hasNoSignedZeros() &&
+      match(&I, m_FNeg(m_OneUse(m_FAdd(m_Value(X), m_Constant(C))))))
+    return BinaryOperator::CreateFSubFMF(ConstantExpr::getFNeg(C), X, &I);
+
   return nullptr;
 }
 
Index: llvm/test/Transforms/InstCombine/fneg.ll
===================================================================
--- llvm/test/Transforms/InstCombine/fneg.ll
+++ llvm/test/Transforms/InstCombine/fneg.ll
@@ -378,6 +378,8 @@
   ret float %sel
 }
 
+; Negative test
+
 define float @fneg_fadd_constant(float %x) {
 ; CHECK-LABEL: @fneg_fadd_constant(
 ; CHECK-NEXT:    [[A:%.*]] = fadd float [[X:%.*]], 4.200000e+01
@@ -389,6 +391,8 @@
   ret float %r
 }
 
+; Negative test
+
 define float @fake_nsz_fadd_constant(float %x) {
 ; CHECK-LABEL: @fake_nsz_fadd_constant(
 ; CHECK-NEXT:    [[A:%.*]] = fadd float [[X:%.*]], 4.200000e+01
@@ -400,12 +404,11 @@
   ret float %r
 }
 
-; TODO: -(x + C) --> -C - x
+; -(x + C) --> -C - x
 
 define float @fneg_nsz_fadd_constant(float %x) {
 ; CHECK-LABEL: @fneg_nsz_fadd_constant(
-; CHECK-NEXT:    [[A:%.*]] = fadd float [[X:%.*]], 4.200000e+01
-; CHECK-NEXT:    [[R:%.*]] = fneg nsz float [[A]]
+; CHECK-NEXT:    [[R:%.*]] = fsub nsz float -4.200000e+01, [[X:%.*]]
 ; CHECK-NEXT:    ret float [[R]]
 ;
   %a = fadd float %x, 42.0
@@ -413,12 +416,11 @@
   ret float %r
 }
 
-; TODO: -(x + C) --> -C - x
+; -(x + C) --> -C - x
 
 define float @fake_fneg_nsz_fadd_constant(float %x) {
 ; CHECK-LABEL: @fake_fneg_nsz_fadd_constant(
-; CHECK-NEXT:    [[A:%.*]] = fadd float [[X:%.*]], 4.200000e+01
-; CHECK-NEXT:    [[R:%.*]] = fsub fast float -0.000000e+00, [[A]]
+; CHECK-NEXT:    [[R:%.*]] = fsub fast float -4.200000e+01, [[X:%.*]]
 ; CHECK-NEXT:    ret float [[R]]
 ;
   %a = fadd float %x, 42.0
@@ -426,6 +428,8 @@
   ret float %r
 }
 
+; Negative test
+
 define float @fneg_nsz_fadd_constant_extra_use(float %x) {
 ; CHECK-LABEL: @fneg_nsz_fadd_constant_extra_use(
 ; CHECK-NEXT:    [[A:%.*]] = fadd float [[X:%.*]], 4.200000e+01
@@ -439,6 +443,8 @@
   ret float %r
 }
 
+; Negative test
+
 define float @fake_fneg_nsz_fadd_constant_extra_use(float %x) {
 ; CHECK-LABEL: @fake_fneg_nsz_fadd_constant_extra_use(
 ; CHECK-NEXT:    [[A:%.*]] = fadd float [[X:%.*]], 4.200000e+01
@@ -452,12 +458,11 @@
   ret float %r
 }
 
-; TODO: -(x + C) --> -C - x
+; -(x + C) --> -C - x
 
 define <2 x float> @fneg_nsz_fadd_constant_vec(<2 x float> %x) {
 ; CHECK-LABEL: @fneg_nsz_fadd_constant_vec(
-; CHECK-NEXT:    [[A:%.*]] = fadd <2 x float> [[X:%.*]], <float 4.200000e+01, float 4.300000e+01>
-; CHECK-NEXT:    [[R:%.*]] = fneg reassoc nnan nsz <2 x float> [[A]]
+; CHECK-NEXT:    [[R:%.*]] = fsub reassoc nnan nsz <2 x float> <float -4.200000e+01, float -4.300000e+01>, [[X:%.*]]
 ; CHECK-NEXT:    ret <2 x float> [[R]]
 ;
   %a = fadd <2 x float> %x, <float 42.0, float 43.0>
@@ -465,12 +470,11 @@
   ret <2 x float> %r
 }
 
-; TODO: -(x + C) --> -C - x
+; -(x + C) --> -C - x
 
 define <2 x float> @fake_fneg_nsz_fadd_constant_vec(<2 x float> %x) {
 ; CHECK-LABEL: @fake_fneg_nsz_fadd_constant_vec(
-; CHECK-NEXT:    [[A:%.*]] = fadd <2 x float> [[X:%.*]], <float 4.200000e+01, float undef>
-; CHECK-NEXT:    [[R:%.*]] = fsub nsz <2 x float> <float undef, float -0.000000e+00>, [[A]]
+; CHECK-NEXT:    [[R:%.*]] = fsub nsz <2 x float> <float -4.200000e+01, float undef>, [[X:%.*]]
 ; CHECK-NEXT:    ret <2 x float> [[R]]
 ;
   %a = fadd <2 x float> %x, <float 42.0, float undef>