Index: llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -1852,6 +1852,29 @@
       if (SimplifyDemandedFPClass(I, 0, DemandedMask, Known, Depth + 1))
         return I;
       break;
+    case Intrinsic::copysign: {
+      // Flip on more potentially demanded classes
+      const FPClassTest DemandedMaskAnySign = llvm::fneg(DemandedMask);
+      if (SimplifyDemandedFPClass(I, 0, DemandedMaskAnySign, Known, Depth + 1))
+        return I;
+
+      if ((DemandedMask & fcPositive) == fcNone) {
+        // Roundabout way of replacing with fneg(fabs)
+        I->setOperand(1, ConstantFP::get(VTy, -1.0));
+        return I;
+      }
+
+      if ((DemandedMask & fcNegative) == fcNone) {
+        // Roundabout way of replacing with fabs
+        I->setOperand(1, ConstantFP::getZero(VTy));
+        return I;
+      }
+
+      KnownFPClass KnownSign = computeKnownFPClass(
+          I->getOperand(1), DL, fcAllFlags, Depth, &TLI, &AC, CxtI, &DT);
+      Known.copysign(KnownSign);
+      break;
+    }
     default:
       Known = computeKnownFPClass(I, DL, ~DemandedMask, Depth + 1, &TLI, &AC,
                                   CxtI, &DT);
Index: llvm/test/Transforms/InstCombine/simplify-demanded-fpclass.ll
===================================================================
--- llvm/test/Transforms/InstCombine/simplify-demanded-fpclass.ll
+++ llvm/test/Transforms/InstCombine/simplify-demanded-fpclass.ll
@@ -524,8 +524,7 @@
 define nofpclass(inf) float @ret_nofpclass_inf__copysign_unknown_select_pinf_rhs(i1 %cond, float %x, float %unknown.sign) {
 ; CHECK-LABEL: define nofpclass(inf) float @ret_nofpclass_inf__copysign_unknown_select_pinf_rhs
 ; CHECK-SAME: (i1 [[COND:%.*]], float [[X:%.*]], float [[UNKNOWN_SIGN:%.*]]) {
-; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[COND]], float [[X]], float 0x7FF0000000000000
-; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[SELECT]], float [[UNKNOWN_SIGN]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[X]], float [[UNKNOWN_SIGN]])
 ; CHECK-NEXT:    ret float [[COPYSIGN]]
 ;
   %select = select i1 %cond, float %x, float 0x7FF0000000000000
@@ -560,7 +559,8 @@
 define nofpclass(pinf pnorm psub pzero) float @ret_nofpclass_nopositives_copysign(float %x, float %unknown.sign) {
 ; CHECK-LABEL: define nofpclass(pinf pzero psub pnorm) float @ret_nofpclass_nopositives_copysign
 ; CHECK-SAME: (float [[X:%.*]], float [[UNKNOWN_SIGN:%.*]]) {
-; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[X]], float [[UNKNOWN_SIGN]])
+; CHECK-NEXT:    [[TMP1:%.*]] = call float @llvm.fabs.f32(float [[X]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = fneg float [[TMP1]]
 ; CHECK-NEXT:    ret float [[COPYSIGN]]
 ;
   %copysign = call float @llvm.copysign.f32(float %x, float %unknown.sign)
@@ -571,7 +571,8 @@
 define nofpclass(pinf pnorm psub pzero) float @ret_nofpclass_nopositives_copysign_nnan_flag(float %x, float %unknown.sign) {
 ; CHECK-LABEL: define nofpclass(pinf pzero psub pnorm) float @ret_nofpclass_nopositives_copysign_nnan_flag
 ; CHECK-SAME: (float [[X:%.*]], float [[UNKNOWN_SIGN:%.*]]) {
-; CHECK-NEXT:    [[COPYSIGN:%.*]] = call nnan float @llvm.copysign.f32(float [[X]], float [[UNKNOWN_SIGN]])
+; CHECK-NEXT:    [[TMP1:%.*]] = call nnan float @llvm.fabs.f32(float [[X]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = fneg nnan float [[TMP1]]
 ; CHECK-NEXT:    ret float [[COPYSIGN]]
 ;
   %copysign = call nnan float @llvm.copysign.f32(float %x, float %unknown.sign)
@@ -582,7 +583,8 @@
 define nofpclass(nan pinf pnorm psub pzero) float @ret_nofpclass_nopositives_nonan_copysign(float %x, float %unknown.sign) {
 ; CHECK-LABEL: define nofpclass(nan pinf pzero psub pnorm) float @ret_nofpclass_nopositives_nonan_copysign
 ; CHECK-SAME: (float [[X:%.*]], float [[UNKNOWN_SIGN:%.*]]) {
-; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[X]], float [[UNKNOWN_SIGN]])
+; CHECK-NEXT:    [[TMP1:%.*]] = call float @llvm.fabs.f32(float [[X]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = fneg float [[TMP1]]
 ; CHECK-NEXT:    ret float [[COPYSIGN]]
 ;
   %copysign = call float @llvm.copysign.f32(float %x, float %unknown.sign)
@@ -593,7 +595,7 @@
 define nofpclass(ninf nnorm nsub nzero) float @ret_nofpclass_nonegatives_copysign(float %x, float %unknown.sign) {
 ; CHECK-LABEL: define nofpclass(ninf nzero nsub nnorm) float @ret_nofpclass_nonegatives_copysign
 ; CHECK-SAME: (float [[X:%.*]], float [[UNKNOWN_SIGN:%.*]]) {
-; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[X]], float [[UNKNOWN_SIGN]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.fabs.f32(float [[X]])
 ; CHECK-NEXT:    ret float [[COPYSIGN]]
 ;
   %copysign = call float @llvm.copysign.f32(float %x, float %unknown.sign)
@@ -604,7 +606,7 @@
 define nofpclass(ninf nnorm nsub nzero) float @ret_nofpclass_nonegatives_copysign_nnan_flag(float %x, float %unknown.sign) {
 ; CHECK-LABEL: define nofpclass(ninf nzero nsub nnorm) float @ret_nofpclass_nonegatives_copysign_nnan_flag
 ; CHECK-SAME: (float [[X:%.*]], float [[UNKNOWN_SIGN:%.*]]) {
-; CHECK-NEXT:    [[COPYSIGN:%.*]] = call nnan float @llvm.copysign.f32(float [[X]], float [[UNKNOWN_SIGN]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = call nnan float @llvm.fabs.f32(float [[X]])
 ; CHECK-NEXT:    ret float [[COPYSIGN]]
 ;
   %copysign = call nnan float @llvm.copysign.f32(float %x, float %unknown.sign)
@@ -615,7 +617,7 @@
 define nofpclass(nan ninf nnorm nsub nzero) float @ret_nofpclass_nonegatives_nonan_copysign(float %x, float %unknown.sign) {
 ; CHECK-LABEL: define nofpclass(nan ninf nzero nsub nnorm) float @ret_nofpclass_nonegatives_nonan_copysign
 ; CHECK-SAME: (float [[X:%.*]], float [[UNKNOWN_SIGN:%.*]]) {
-; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[X]], float [[UNKNOWN_SIGN]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.fabs.f32(float [[X]])
 ; CHECK-NEXT:    ret float [[COPYSIGN]]
 ;
   %copysign = call float @llvm.copysign.f32(float %x, float %unknown.sign)
@@ -638,8 +640,7 @@
 define nofpclass(inf nnorm nsub nzero) float @ret_nofpclass_no_negatives_noinf__copysign_unknown_select_pinf_rhs(i1 %cond, float %x, float %unknown.sign) {
 ; CHECK-LABEL: define nofpclass(inf nzero nsub nnorm) float @ret_nofpclass_no_negatives_noinf__copysign_unknown_select_pinf_rhs
 ; CHECK-SAME: (i1 [[COND:%.*]], float [[X:%.*]], float [[UNKNOWN_SIGN:%.*]]) {
-; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[COND]], float [[X]], float 0x7FF0000000000000
-; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[SELECT]], float [[UNKNOWN_SIGN]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.fabs.f32(float [[X]])
 ; CHECK-NEXT:    ret float [[COPYSIGN]]
 ;
   %select = select i1 %cond, float %x, float 0x7FF0000000000000
@@ -651,8 +652,8 @@
 define nofpclass(inf pnorm psub pzero) float @ret_nofpclass_no_positives_noinf__copysign_unknown_select_pinf_rhs(i1 %cond, float %x, float %unknown.sign) {
 ; CHECK-LABEL: define nofpclass(inf pzero psub pnorm) float @ret_nofpclass_no_positives_noinf__copysign_unknown_select_pinf_rhs
 ; CHECK-SAME: (i1 [[COND:%.*]], float [[X:%.*]], float [[UNKNOWN_SIGN:%.*]]) {
-; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[COND]], float [[X]], float 0x7FF0000000000000
-; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[SELECT]], float [[UNKNOWN_SIGN]])
+; CHECK-NEXT:    [[TMP1:%.*]] = call float @llvm.fabs.f32(float [[X]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = fneg float [[TMP1]]
 ; CHECK-NEXT:    ret float [[COPYSIGN]]
 ;
   %select = select i1 %cond, float %x, float 0x7FF0000000000000
@@ -664,8 +665,7 @@
 define nofpclass(ninf nnorm nsub nzero) float @ret_nofpclass_no_negatives__copysign_unknown_select_pinf_rhs(i1 %cond, float %x, float %unknown.sign) {
 ; CHECK-LABEL: define nofpclass(ninf nzero nsub nnorm) float @ret_nofpclass_no_negatives__copysign_unknown_select_pinf_rhs
 ; CHECK-SAME: (i1 [[COND:%.*]], float [[X:%.*]], float [[UNKNOWN_SIGN:%.*]]) {
-; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[COND]], float [[X]], float 0x7FF0000000000000
-; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[SELECT]], float [[UNKNOWN_SIGN]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.fabs.f32(float [[X]])
 ; CHECK-NEXT:    ret float [[COPYSIGN]]
 ;
   %select = select i1 %cond, float %x, float 0x7FF0000000000000
@@ -678,7 +678,8 @@
 ; CHECK-LABEL: define nofpclass(pinf pzero psub pnorm) float @ret_nofpclass_no_positives__copysign_unknown_select_pinf_rhs
 ; CHECK-SAME: (i1 [[COND:%.*]], float [[X:%.*]], float [[UNKNOWN_SIGN:%.*]]) {
 ; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[COND]], float [[X]], float 0x7FF0000000000000
-; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[SELECT]], float [[UNKNOWN_SIGN]])
+; CHECK-NEXT:    [[TMP1:%.*]] = call float @llvm.fabs.f32(float [[SELECT]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = fneg float [[TMP1]]
 ; CHECK-NEXT:    ret float [[COPYSIGN]]
 ;
   %select = select i1 %cond, float %x, float 0x7FF0000000000000
@@ -690,8 +691,7 @@
 define nofpclass(nan ninf nnorm nsub nzero) float @ret_nofpclass_no_negatives_nonan__copysign_unknown_select_pinf_rhs(i1 %cond, float %x, float %unknown.sign) {
 ; CHECK-LABEL: define nofpclass(nan ninf nzero nsub nnorm) float @ret_nofpclass_no_negatives_nonan__copysign_unknown_select_pinf_rhs
 ; CHECK-SAME: (i1 [[COND:%.*]], float [[X:%.*]], float [[UNKNOWN_SIGN:%.*]]) {
-; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[COND]], float [[X]], float 0x7FF0000000000000
-; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[SELECT]], float [[UNKNOWN_SIGN]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.fabs.f32(float [[X]])
 ; CHECK-NEXT:    ret float [[COPYSIGN]]
 ;
   %select = select i1 %cond, float %x, float 0x7FF0000000000000
@@ -704,7 +704,8 @@
 ; CHECK-LABEL: define nofpclass(nan pinf pzero psub pnorm) float @ret_nofpclass_no_positives_nonan__copysign_unknown_select_pinf_rhs
 ; CHECK-SAME: (i1 [[COND:%.*]], float [[X:%.*]], float [[UNKNOWN_SIGN:%.*]]) {
 ; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[COND]], float [[X]], float 0x7FF0000000000000
-; CHECK-NEXT:    [[COPYSIGN:%.*]] = call float @llvm.copysign.f32(float [[SELECT]], float [[UNKNOWN_SIGN]])
+; CHECK-NEXT:    [[TMP1:%.*]] = call float @llvm.fabs.f32(float [[SELECT]])
+; CHECK-NEXT:    [[COPYSIGN:%.*]] = fneg float [[TMP1]]
 ; CHECK-NEXT:    ret float [[COPYSIGN]]
 ;
   %select = select i1 %cond, float %x, float 0x7FF0000000000000