Index: lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -1234,6 +1234,14 @@
     return &I;
   }
 
+  // X / fabs(X) -> copysign(1.0, X)
+  if (I.hasNoNaNs() && I.hasNoInfs() &&
+      match(Op1, m_Intrinsic<Intrinsic::fabs>(m_Specific(Op0))) &&
+      Op1->hasOneUse()) {
+    Value *V = Builder.CreateBinaryIntrinsic(
+        Intrinsic::copysign, ConstantFP::get(I.getType(), 1.0), Op0, &I);
+    return replaceInstUsesWith(I, V);
+  }
   return nullptr;
 }
 
Index: test/Transforms/InstCombine/fabs-copysign.ll
===================================================================
--- test/Transforms/InstCombine/fabs-copysign.ll
+++ test/Transforms/InstCombine/fabs-copysign.ll
@@ -3,6 +3,7 @@
 
 declare double @llvm.fabs.f64(double)
 declare float @llvm.fabs.f32(float)
+declare <4 x double> @llvm.fabs.v4f64(<4 x double>)
 declare void @use(double)
 
 declare double @llvm.copysign.f64(double, double)
@@ -10,21 +11,29 @@
 
 define double @fabs_copysign(double %x) {
 ; CHECK-LABEL: @fabs_copysign(
-; CHECK-NEXT:    [[F:%.*]] = tail call double @llvm.fabs.f64(double [[X:%.*]])
-; CHECK-NEXT:    [[DIV:%.*]] = fdiv nnan ninf double [[X]], [[F]]
-; CHECK-NEXT:    ret double [[DIV]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call nnan ninf double @llvm.copysign.f64(double 1.000000e+00, double [[X:%.*]])
+; CHECK-NEXT:    ret double [[TMP1]]
 ;
   %f = tail call double @llvm.fabs.f64(double %x)
   %div = fdiv nnan ninf double %x, %f
   ret double %div
 }
 
+define <4 x double> @fabs_copysign_vec(<4 x double> %x) {
+; CHECK-LABEL: @fabs_copysign_vec(
+; CHECK-NEXT:    [[TMP1:%.*]] = call nnan ninf <4 x double> @llvm.copysign.v4f64(<4 x double> <double 1.000000e+00, double 1.000000e+00, double 1.000000e+00, double 1.000000e+00>, <4 x double> [[X:%.*]])
+; CHECK-NEXT:    ret <4 x double> [[TMP1]]
+;
+  %f = call <4 x double> @llvm.fabs.v4f64(<4 x double> %x)
+  %div = fdiv nnan ninf <4 x double> %x, %f
+  ret <4 x double> %div
+}
+
 
 define float @fabs_copysignf(float %x) {
 ; CHECK-LABEL: @fabs_copysignf(
-; CHECK-NEXT:    [[F:%.*]] = tail call float @llvm.fabs.f32(float [[X:%.*]])
-; CHECK-NEXT:    [[DIV:%.*]] = fdiv nnan ninf float [[X]], [[F]]
-; CHECK-NEXT:    ret float [[DIV]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call nnan ninf float @llvm.copysign.f32(float 1.000000e+00, float [[X:%.*]])
+; CHECK-NEXT:    ret float [[TMP1]]
 ;
   %f = tail call float @llvm.fabs.f32(float %x)
   %div = fdiv nnan ninf float %x, %f
@@ -33,9 +42,8 @@
 
 define double @fabs_copysign_use(double %x) {
 ; CHECK-LABEL: @fabs_copysign_use(
-; CHECK-NEXT:    [[F:%.*]] = tail call double @llvm.fabs.f64(double [[X:%.*]])
-; CHECK-NEXT:    [[DIV:%.*]] = fdiv nnan ninf double [[X]], [[F]]
-; CHECK-NEXT:    ret double [[DIV]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call nnan ninf double @llvm.copysign.f64(double 1.000000e+00, double [[X:%.*]])
+; CHECK-NEXT:    ret double [[TMP1]]
 ;
   %f = tail call double @llvm.fabs.f64(double %x)
   %div = fdiv nnan ninf double %x, %f
@@ -47,11 +55,11 @@
 define double @fabs_copysign_mismatch(double %x, double %y) {
 ; CHECK-LABEL: @fabs_copysign_mismatch(
 ; CHECK-NEXT:    [[F:%.*]] = tail call double @llvm.fabs.f64(double [[Y:%.*]])
-; CHECK-NEXT:    [[DIV:%.*]] = fdiv double [[X:%.*]], [[F]]
+; CHECK-NEXT:    [[DIV:%.*]] = fdiv nnan ninf double [[X:%.*]], [[F]]
 ; CHECK-NEXT:    ret double [[DIV]]
 ;
   %f = tail call double @llvm.fabs.f64(double %y)
-  %div = fdiv double %x, %f
+  %div = fdiv nnan ninf double %x, %f
   ret double %div
 }