diff --git a/llvm/test/Transforms/InstCombine/fsub.ll b/llvm/test/Transforms/InstCombine/fsub.ll
index e7b5a073c246..359462638d37 100644
--- a/llvm/test/Transforms/InstCombine/fsub.ll
+++ b/llvm/test/Transforms/InstCombine/fsub.ll
@@ -3,20 +3,20 @@
 
 ; PR4374
 
-define float @test1(float %a, float %b) nounwind {
+define float @test1(float %a, float %b) {
 ; CHECK-LABEL: @test1(
 ; CHECK-NEXT:    [[T1:%.*]] = fsub float [[A:%.*]], [[B:%.*]]
 ; CHECK-NEXT:    [[T2:%.*]] = fsub float -0.000000e+00, [[T1]]
 ; CHECK-NEXT:    ret float [[T2]]
 ;
   %t1 = fsub float %a, %b
-  %t2 = fsub float -0.000000e+00, %t1
+  %t2 = fsub float -0.0, %t1
   ret float %t2
 }
 
 ; <rdar://problem/7530098>
 
-define double @test2(double %x, double %y) nounwind {
+define double @test2(double %x, double %y) {
 ; CHECK-LABEL: @test2(
 ; CHECK-NEXT:    [[T1:%.*]] = fadd double [[X:%.*]], [[Y:%.*]]
 ; CHECK-NEXT:    [[T2:%.*]] = fsub double [[X]], [[T1]]
@@ -27,3 +27,65 @@ define double @test2(double %x, double %y) nounwind {
   ret double %t2
 }
 
+; X - C --> X + (-C)
+
+define float @constant_op1(float %x, float %y) {
+; CHECK-LABEL: @constant_op1(
+; CHECK-NEXT:    [[R:%.*]] = fadd float [[X:%.*]], -4.200000e+01
+; CHECK-NEXT:    ret float [[R]]
+;
+  %r = fsub float %x, 42.0
+  ret float %r
+}
+
+define <2 x float> @constant_op1_vec(<2 x float> %x, <2 x float> %y) {
+; CHECK-LABEL: @constant_op1_vec(
+; CHECK-NEXT:    [[R:%.*]] = fadd <2 x float> [[X:%.*]], <float -4.200000e+01, float 4.200000e+01>
+; CHECK-NEXT:    ret <2 x float> [[R]]
+;
+  %r = fsub <2 x float> %x, <float 42.0, float -42.0>
+  ret <2 x float> %r
+}
+
+define <2 x float> @constant_op1_vec_undef(<2 x float> %x, <2 x float> %y) {
+; CHECK-LABEL: @constant_op1_vec_undef(
+; CHECK-NEXT:    [[R:%.*]] = fsub <2 x float> [[X:%.*]], <float undef, float -4.200000e+01>
+; CHECK-NEXT:    ret <2 x float> [[R]]
+;
+  %r = fsub <2 x float> %x, <float undef, float -42.0>
+  ret <2 x float> %r
+}
+
+; X - (-Y) --> X + Y
+
+define float @neg_op1(float %x, float %y) {
+; CHECK-LABEL: @neg_op1(
+; CHECK-NEXT:    [[R:%.*]] = fadd float [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    ret float [[R]]
+;
+  %negy = fsub float -0.0, %y
+  %r = fsub float %x, %negy
+  ret float %r
+}
+
+define <2 x float> @neg_op1_vec(<2 x float> %x, <2 x float> %y) {
+; CHECK-LABEL: @neg_op1_vec(
+; CHECK-NEXT:    [[R:%.*]] = fadd <2 x float> [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x float> [[R]]
+;
+  %negy = fsub <2 x float> <float -0.0, float -0.0>, %y
+  %r = fsub <2 x float> %x, %negy
+  ret <2 x float> %r
+}
+
+define <2 x float> @neg_op1_vec_undef(<2 x float> %x, <2 x float> %y) {
+; CHECK-LABEL: @neg_op1_vec_undef(
+; CHECK-NEXT:    [[NEGY:%.*]] = fsub <2 x float> <float -0.000000e+00, float undef>, [[Y:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = fsub <2 x float> [[X:%.*]], [[NEGY]]
+; CHECK-NEXT:    ret <2 x float> [[R]]
+;
+  %negy = fsub <2 x float> <float -0.0, float undef>, %y
+  %r = fsub <2 x float> %x, %negy
+  ret <2 x float> %r
+}
+