diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 7aac13fd474b2..cbb69887642ba 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3229,16 +3229,16 @@ Instruction *InstCombinerImpl::foldICmpBitCast(ICmpInst &Cmp) {
       if (Cmp.isEquality() && match(Op1, m_Zero()))
         return new ICmpInst(Pred, X, ConstantInt::getNullValue(X->getType()));
 
-    // If this is a sign-bit test of a bitcast of a casted FP value, eliminate
-    // the FP extend/truncate because that cast does not change the sign-bit.
-    // This is true for all standard IEEE-754 types and the X86 80-bit type.
-    // The sign-bit is always the most significant bit in those types.
     const APInt *C;
     bool TrueIfSigned;
-    if (match(Op1, m_APInt(C)) && Bitcast->hasOneUse() &&
-        isSignBitCheck(Pred, *C, TrueIfSigned)) {
-      if (match(BCSrcOp, m_FPExt(m_Value(X))) ||
-          match(BCSrcOp, m_FPTrunc(m_Value(X)))) {
+    if (match(Op1, m_APInt(C)) && Bitcast->hasOneUse()) {
+      // If this is a sign-bit test of a bitcast of a casted FP value, eliminate
+      // the FP extend/truncate because that cast does not change the sign-bit.
+      // This is true for all standard IEEE-754 types and the X86 80-bit type.
+      // The sign-bit is always the most significant bit in those types.
+      if (isSignBitCheck(Pred, *C, TrueIfSigned) &&
+          (match(BCSrcOp, m_FPExt(m_Value(X))) ||
+           match(BCSrcOp, m_FPTrunc(m_Value(X))))) {
         // (bitcast (fpext/fptrunc X)) to iX) < 0 --> (bitcast X to iY) < 0
         // (bitcast (fpext/fptrunc X)) to iX) > -1 --> (bitcast X to iY) > -1
         Type *XType = X->getType();
@@ -3257,6 +3257,20 @@ Instruction *InstCombinerImpl::foldICmpBitCast(ICmpInst &Cmp) {
                                 ConstantInt::getAllOnesValue(NewType));
         }
       }
+
+      // icmp eq/ne (bitcast X to int), special fp -> llvm.is.fpclass(X, class)
+      Type *FPType = SrcType->getScalarType();
+      if (!Cmp.getParent()->getParent()->hasFnAttribute(
+              Attribute::NoImplicitFloat) &&
+          Cmp.isEquality() && FPType->isIEEELikeFPTy()) {
+        FPClassTest Mask = APFloat(FPType->getFltSemantics(), *C).classify();
+        if (Mask & (fcInf | fcZero)) {
+          if (Pred == ICmpInst::ICMP_NE)
+            Mask = ~Mask;
+          return replaceInstUsesWith(Cmp,
+                                     Builder.createIsFPClass(BCSrcOp, Mask));
+        }
+      }
     }
   }
 
diff --git a/llvm/test/Transforms/InstCombine/fpclass-check-idioms.ll b/llvm/test/Transforms/InstCombine/fpclass-check-idioms.ll
index 019db343c61cc..d2b4536448ebd 100644
--- a/llvm/test/Transforms/InstCombine/fpclass-check-idioms.ll
+++ b/llvm/test/Transforms/InstCombine/fpclass-check-idioms.ll
@@ -40,13 +40,11 @@ define i1 @f64_fcnan_fcinf(double %a) {
   ret i1 %cmp
 }
 
-; TODO: handle more fpclass check idioms
 define i1 @f32_fcinf(float %a) {
 ; CHECK-LABEL: define i1 @f32_fcinf(
 ; CHECK-SAME: float [[A:%.*]]) {
 ; CHECK-NEXT:    [[TMP1:%.*]] = call float @llvm.fabs.f32(float [[A]])
-; CHECK-NEXT:    [[AND:%.*]] = bitcast float [[TMP1]] to i32
-; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[AND]], 2139095040
+; CHECK-NEXT:    [[CMP:%.*]] = fcmp oeq float [[TMP1]], 0x7FF0000000000000
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %i32 = bitcast float %a to i32
@@ -55,6 +53,63 @@ define i1 @f32_fcinf(float %a) {
   ret i1 %cmp
 }
 
+define i1 @f32_fcposinf(float %a) {
+; CHECK-LABEL: define i1 @f32_fcposinf(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT:    [[CMP:%.*]] = fcmp oeq float [[A]], 0x7FF0000000000000
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i32 = bitcast float %a to i32
+  %cmp = icmp eq i32 %i32, 2139095040
+  ret i1 %cmp
+}
+
+define i1 @f32_fcneginf(float %a) {
+; CHECK-LABEL: define i1 @f32_fcneginf(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT:    [[CMP:%.*]] = fcmp oeq float [[A]], 0xFFF0000000000000
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i32 = bitcast float %a to i32
+  %cmp = icmp eq i32 %i32, 4286578688
+  ret i1 %cmp
+}
+
+define i1 @f32_fcposzero(float %a) {
+; CHECK-LABEL: define i1 @f32_fcposzero(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT:    [[CMP:%.*]] = call i1 @llvm.is.fpclass.f32(float [[A]], i32 64)
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i32 = bitcast float %a to i32
+  %cmp = icmp eq i32 %i32, 0
+  ret i1 %cmp
+}
+
+define i1 @f32_fcnegzero(float %a) {
+; CHECK-LABEL: define i1 @f32_fcnegzero(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT:    [[CMP:%.*]] = call i1 @llvm.is.fpclass.f32(float [[A]], i32 32)
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i32 = bitcast float %a to i32
+  %cmp = icmp eq i32 %i32, 2147483648
+  ret i1 %cmp
+}
+
+define i1 @f32_fczero(float %a) {
+; CHECK-LABEL: define i1 @f32_fczero(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT:    [[CMP:%.*]] = fcmp oeq float [[A]], 0.000000e+00
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i32 = bitcast float %a to i32
+  %and = and i32 %i32, 2147483647
+  %cmp = icmp eq i32 %and, 0
+  ret i1 %cmp
+}
+
+; TODO: handle more fpclass check idioms
 define i1 @f32_fcnan(float %a) {
 ; CHECK-LABEL: define i1 @f32_fcnan(
 ; CHECK-SAME: float [[A:%.*]]) {
@@ -101,6 +156,19 @@ define <2 x i1> @f32_fcnan_fcinf_vec(<2 x float> %a) {
   ret <2 x i1> %cmp
 }
 
+define <2 x i1> @f32_fcinf_vec(<2 x float> %a) {
+; CHECK-LABEL: define <2 x i1> @f32_fcinf_vec(
+; CHECK-SAME: <2 x float> [[A:%.*]]) {
+; CHECK-NEXT:    [[TMP1:%.*]] = call <2 x float> @llvm.fabs.v2f32(<2 x float> [[A]])
+; CHECK-NEXT:    [[CMP:%.*]] = fcmp oeq <2 x float> [[TMP1]], <float 0x7FF0000000000000, float 0x7FF0000000000000>
+; CHECK-NEXT:    ret <2 x i1> [[CMP]]
+;
+  %i32 = bitcast <2 x float> %a to <2 x i32>
+  %and = and <2 x i32> %i32, <i32 2147483647, i32 2147483647>
+  %cmp = icmp eq <2 x i32> %and, <i32 2139095040, i32 2139095040>
+  ret <2 x i1> %cmp
+}
+
 ; Negative tests
 
 define i1 @f32_fcnan_fcinf_wrong_mask1(float %a) {
@@ -158,6 +226,18 @@ define i1 @f32_fcnan_fcinf_wrong_pred(float %a) {
   ret i1 %cmp
 }
 
+define i1 @f32_fcposzero_wrong_pred(float %a) {
+; CHECK-LABEL: define i1 @f32_fcposzero_wrong_pred(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT:    [[I32:%.*]] = bitcast float [[A]] to i32
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[I32]], 0
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i32 = bitcast float %a to i32
+  %cmp = icmp slt i32 %i32, 0
+  ret i1 %cmp
+}
+
 define i1 @f32_fcnan_fcinf_wrong_type1(<2 x float> %a) {
 ; CHECK-LABEL: define i1 @f32_fcnan_fcinf_wrong_type1(
 ; CHECK-SAME: <2 x float> [[A:%.*]]) {
@@ -172,6 +252,18 @@ define i1 @f32_fcnan_fcinf_wrong_type1(<2 x float> %a) {
   ret i1 %cmp
 }
 
+define i1 @f32_fcposinf_wrong_type1(<2 x float> %a) {
+; CHECK-LABEL: define i1 @f32_fcposinf_wrong_type1(
+; CHECK-SAME: <2 x float> [[A:%.*]]) {
+; CHECK-NEXT:    [[I64:%.*]] = bitcast <2 x float> [[A]] to i64
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i64 [[I64]], 2139095040
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i64 = bitcast <2 x float> %a to i64
+  %cmp = icmp eq i64 %i64, 2139095040
+  ret i1 %cmp
+}
+
 define i1 @f32_fcnan_fcinf_wrong_type2(x86_fp80 %a) {
 ; CHECK-LABEL: define i1 @f32_fcnan_fcinf_wrong_type2(
 ; CHECK-SAME: x86_fp80 [[A:%.*]]) {
@@ -186,6 +278,18 @@ define i1 @f32_fcnan_fcinf_wrong_type2(x86_fp80 %a) {
   ret i1 %cmp
 }
 
+define i1 @f32_fcposzero_wrong_type2(x86_fp80 %a) {
+; CHECK-LABEL: define i1 @f32_fcposzero_wrong_type2(
+; CHECK-SAME: x86_fp80 [[A:%.*]]) {
+; CHECK-NEXT:    [[I80:%.*]] = bitcast x86_fp80 [[A]] to i80
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i80 [[I80]], 0
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i80 = bitcast x86_fp80 %a to i80
+  %cmp = icmp eq i80 %i80, 0
+  ret i1 %cmp
+}
+
 define i1 @f32_fcnan_fcinf_noimplicitfloat(float %a) #0 {
 ; CHECK-LABEL: define i1 @f32_fcnan_fcinf_noimplicitfloat(
 ; CHECK-SAME: float [[A:%.*]]) #[[ATTR1:[0-9]+]] {
@@ -200,4 +304,44 @@ define i1 @f32_fcnan_fcinf_noimplicitfloat(float %a) #0 {
   ret i1 %cmp
 }
 
+define i1 @f32_fcposinf_noimplicitfloat(float %a) #0 {
+; CHECK-LABEL: define i1 @f32_fcposinf_noimplicitfloat(
+; CHECK-SAME: float [[A:%.*]]) #[[ATTR1]] {
+; CHECK-NEXT:    [[I32:%.*]] = bitcast float [[A]] to i32
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[I32]], 2139095040
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i32 = bitcast float %a to i32
+  %cmp = icmp eq i32 %i32, 2139095040
+  ret i1 %cmp
+}
+
+define i1 @f32_fcposnan(float %a) {
+; CHECK-LABEL: define i1 @f32_fcposnan(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT:    [[I32:%.*]] = bitcast float [[A]] to i32
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[I32]], 2139095041
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i32 = bitcast float %a to i32
+  %cmp = icmp eq i32 %i32, 2139095041
+  ret i1 %cmp
+}
+
+define i1 @f32_fcposinf_multiuse(float %a) {
+; CHECK-LABEL: define i1 @f32_fcposinf_multiuse(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT:    [[I32:%.*]] = bitcast float [[A]] to i32
+; CHECK-NEXT:    call void @usei32(i32 [[I32]])
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[I32]], 2139095040
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i32 = bitcast float %a to i32
+  call void @usei32(i32 %i32)
+  %cmp = icmp eq i32 %i32, 2139095040
+  ret i1 %cmp
+}
+
+declare void @usei32(i32)
+
 attributes #0 = { noimplicitfloat }