Index: lib/CodeGen/SelectionDAG/SelectionDAG.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -4818,7 +4818,7 @@
     case ISD::FMUL:
     case ISD::FDIV:
     case ISD::FREM:
-      if (getTarget().Options.UnsafeFPMath)
+      if (getTarget().Options.UnsafeFPMath || Flags.isFast())
         return N2;
       break;
     case ISD::MUL:
Index: test/CodeGen/X86/fp-undef.ll
===================================================================
--- test/CodeGen/X86/fp-undef.ll
+++ test/CodeGen/X86/fp-undef.ll
@@ -14,7 +14,7 @@
 ; UNSAFE-LABEL: fadd_undef_op0:
 ; UNSAFE:       # %bb.0:
 ; UNSAFE-NEXT:    retq
-  %r = fadd float undef, %x
+  %r = fadd fast float undef, %x
   ret float %r
 }
 
@@ -27,7 +27,7 @@
 ; UNSAFE-LABEL: fadd_undef_op1:
 ; UNSAFE:       # %bb.0:
 ; UNSAFE-NEXT:    retq
-  %r = fadd float %x, undef
+  %r = fadd fast float %x, undef
   ret float %r
 }
 
@@ -35,7 +35,7 @@
 ; ANY-LABEL: fsub_undef_op0:
 ; ANY:       # %bb.0:
 ; ANY-NEXT:    retq
-  %r = fsub float undef, %x
+  %r = fsub fast float undef, %x
   ret float %r
 }
 
@@ -48,7 +48,7 @@
 ; UNSAFE-LABEL: fsub_undef_op1:
 ; UNSAFE:       # %bb.0:
 ; UNSAFE-NEXT:    retq
-  %r = fsub float %x, undef
+  %r = fsub fast float %x, undef
   ret float %r
 }
 
@@ -61,7 +61,7 @@
 ; UNSAFE-LABEL: fmul_undef_op0:
 ; UNSAFE:       # %bb.0:
 ; UNSAFE-NEXT:    retq
-  %r = fmul float undef, %x
+  %r = fmul fast float undef, %x
   ret float %r
 }
 
@@ -74,7 +74,7 @@
 ; UNSAFE-LABEL: fmul_undef_op1:
 ; UNSAFE:       # %bb.0:
 ; UNSAFE-NEXT:    retq
-  %r = fmul float %x, undef
+  %r = fmul fast float %x, undef
   ret float %r
 }
 
@@ -82,7 +82,7 @@
 ; ANY-LABEL: fdiv_undef_op0:
 ; ANY:       # %bb.0:
 ; ANY-NEXT:    retq
-  %r = fdiv float undef, %x
+  %r = fdiv fast float undef, %x
   ret float %r
 }
 
@@ -95,7 +95,7 @@
 ; UNSAFE-LABEL: fdiv_undef_op1:
 ; UNSAFE:       # %bb.0:
 ; UNSAFE-NEXT:    retq
-  %r = fdiv float %x, undef
+  %r = fdiv fast float %x, undef
   ret float %r
 }
 
@@ -103,7 +103,7 @@
 ; ANY-LABEL: frem_undef_op0:
 ; ANY:       # %bb.0:
 ; ANY-NEXT:    retq
-  %r = frem float undef, %x
+  %r = frem fast float undef, %x
   ret float %r
 }
 
@@ -115,7 +115,7 @@
 ; UNSAFE-LABEL: frem_undef_op1:
 ; UNSAFE:       # %bb.0:
 ; UNSAFE-NEXT:    retq
-  %r = frem float %x, undef
+  %r = frem fast float %x, undef
   ret float %r
 }
 
@@ -424,7 +424,6 @@
 define double @fadd_undef_op1_fast_constant_nan(double %x) {
 ; STRICT-LABEL: fadd_undef_op1_fast_constant_nan:
 ; STRICT:       # %bb.0:
-; STRICT-NEXT:    addsd {{.*}}(%rip), %xmm0
 ; STRICT-NEXT:    retq
 ;
 ; UNSAFE-LABEL: fadd_undef_op1_fast_constant_nan:
@@ -472,7 +471,6 @@
 define double @fmul_undef_op1_fast_constant_nan(double %x) {
 ; STRICT-LABEL: fmul_undef_op1_fast_constant_nan:
 ; STRICT:       # %bb.0:
-; STRICT-NEXT:    mulsd {{.*}}(%rip), %xmm0
 ; STRICT-NEXT:    retq
 ;
 ; UNSAFE-LABEL: fmul_undef_op1_fast_constant_nan:
@@ -543,7 +541,6 @@
 define double @fadd_undef_op1_fast_constant_inf(double %x) {
 ; STRICT-LABEL: fadd_undef_op1_fast_constant_inf:
 ; STRICT:       # %bb.0:
-; STRICT-NEXT:    addsd {{.*}}(%rip), %xmm0
 ; STRICT-NEXT:    retq
 ;
 ; UNSAFE-LABEL: fadd_undef_op1_fast_constant_inf:
@@ -591,7 +588,6 @@
 define double @fmul_undef_op1_fast_constant_inf(double %x) {
 ; STRICT-LABEL: fmul_undef_op1_fast_constant_inf:
 ; STRICT:       # %bb.0:
-; STRICT-NEXT:    mulsd {{.*}}(%rip), %xmm0
 ; STRICT-NEXT:    retq
 ;
 ; UNSAFE-LABEL: fmul_undef_op1_fast_constant_inf: