diff --git a/llvm/include/llvm/ADT/APFloat.h b/llvm/include/llvm/ADT/APFloat.h
index 82ac9a3a1ef80..32e5c1aafc245 100644
--- a/llvm/include/llvm/ADT/APFloat.h
+++ b/llvm/include/llvm/ADT/APFloat.h
@@ -1149,6 +1149,19 @@ class APFloat : public APFloatBase {
   /// \param Semantics - type float semantics
   LLVM_ABI static APFloat getAllOnesValue(const fltSemantics &Semantics);
 
+  /// Returns a copy of this APFloat with the requested semantics.
+  /// The requested semantics should be equal to or stronger
+  /// than the semantics of the current instance.
+  APFloat getPromoted(const fltSemantics &Sem) const {
+    assert(isRepresentableBy(this->getSemantics(), Sem) &&
+           "Target semantics will lose information.");
+    APFloat Val(*this);
+    bool LosesInfo;
+    Val.convert(Sem, rmNearestTiesToEven, &LosesInfo);
+    assert(!LosesInfo);
+    return Val;
+  }
+
   /// Returns true if the given semantics has actual significand.
   ///
   /// \param Sem - type float semantics
diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index da32542cf7870..0253606c4eedb 100755
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -1996,7 +1996,9 @@ bool llvm::canConstantFoldCallTo(const CallBase *Call, const Function *F) {
            Name == "log10f" || Name == "logb" || Name == "logbf" ||
            Name == "log1p" || Name == "log1pf";
   case 'n':
-    return Name == "nearbyint" || Name == "nearbyintf";
+    return Name == "nearbyint" || Name == "nearbyintf" || Name == "nextafter" ||
+           Name == "nextafterf" || Name == "nexttoward" ||
+           Name == "nexttowardf";
   case 'p':
     return Name == "pow" || Name == "powf";
   case 'r':
@@ -3221,6 +3223,35 @@ static Constant *ConstantFoldLibCall2(StringRef Name, Type *Ty,
     if (TLI->has(Func))
       return ConstantFoldBinaryFP(atan2, Op1V, Op2V, Ty);
     break;
+  case LibFunc_nextafter:
+  case LibFunc_nextafterf:
+  case LibFunc_nexttoward:
+  case LibFunc_nexttowardf:
+    if (TLI->has(Func)) {
+      if (Op1V.isNaN())
+        return ConstantFP::get(Ty->getContext(), Op1V);
+      if (Op2V.isNaN()) {
+        // IEEE 754, 6.5.4 recommends the inclusion of diagnostic
+        // information if the NaN payload can't be preserved. Should
+        // we do something special here?
+        const bool SemEqual = &Op2V.getSemantics() == &Ty->getFltSemantics();
+        const APFloat Ret =
+            SemEqual ? Op2V : APFloat::getNaN(Ty->getFltSemantics());
+        return ConstantFP::get(Ty->getContext(), Ret);
+      }
+
+      // The two arguments of nexttoward can have differing semantics.
+      // We need to convert both arguments to the same semantics so
+      // we can do comparisons.
+      const APFloat PromotedOp1V = Op1V.getPromoted(APFloat::IEEEquad());
+      const APFloat PromotedOp2V = Op2V.getPromoted(APFloat::IEEEquad());
+      if (PromotedOp1V == PromotedOp2V)
+        return ConstantFP::get(Ty->getContext(), Op1V);
+
+      APFloat Next(Op1V);
+      Next.next(/*nextDown=*/PromotedOp1V > PromotedOp2V);
+      return ConstantFP::get(Ty->getContext(), Next);
+    }
   }
 
   return nullptr;
@@ -4655,6 +4686,25 @@ bool llvm::isMathLibCallNoop(const CallBase *Call,
         // may occur, so allow for that possibility.
         return !Op0.isZero() || !Op1.isZero();
 
+      case LibFunc_nextafter:
+      case LibFunc_nextafterf:
+      case LibFunc_nextafterl:
+      case LibFunc_nexttoward:
+      case LibFunc_nexttowardf:
+      case LibFunc_nexttowardl: {
+        // The two arguments of nexttoward can have differing semantics.
+        // We need to convert both arguments to the same semantics so
+        // we can do comparisons.
+        const APFloat PromotedOp0 = Op0.getPromoted(APFloat::IEEEquad());
+        const APFloat PromotedOp1 = Op1.getPromoted(APFloat::IEEEquad());
+        if (PromotedOp0 == PromotedOp1)
+          return true;
+
+        APFloat Next(Op0);
+        Next.next(/*nextDown=*/PromotedOp0 > PromotedOp1);
+        const bool DidOverflow = Op0.isLargest() && Next.isInfinity();
+        return !Next.isZero() && !Next.isDenormal() && !DidOverflow;
+      }
       default:
         break;
       }
diff --git a/llvm/test/Transforms/InstCombine/constant-fold-nextafter.ll b/llvm/test/Transforms/InstCombine/constant-fold-nextafter.ll
new file mode 100644
index 0000000000000..5ffcaef5be9c0
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/constant-fold-nextafter.ll
@@ -0,0 +1,212 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: cat %S/floating-point-constants.ll %s | opt -passes=instcombine -S | FileCheck %s
+
+declare double @nextafter(double noundef, double noundef) #0
+declare float @nextafterf(float noundef, float noundef) #0
+
+attributes #0 = { willreturn memory(errnomem: write) }
+
+; ==================
+; nextafter tests
+; ==================
+
+define double @nextafter_can_constant_fold_up_direction() {
+; CHECK-LABEL: define double @nextafter_can_constant_fold_up_direction() {
+; CHECK-NEXT:    ret double 0x3FF0000000000001
+;
+  %next = call double @nextafter(double noundef 1.0, double noundef 2.0)
+  ret double %next
+}
+define double @nextafter_can_constant_fold_down_direction() {
+; CHECK-LABEL: define double @nextafter_can_constant_fold_down_direction() {
+; CHECK-NEXT:    ret double 0x3FEFFFFFFFFFFFFF
+;
+  %next = call double @nextafter(double noundef 1.0, double noundef 0.0)
+  ret double %next
+}
+define double @nextafter_can_constant_fold_equal_args() {
+; CHECK-LABEL: define double @nextafter_can_constant_fold_equal_args() {
+; CHECK-NEXT:    ret double 1.000000e+00
+;
+  %next = call double @nextafter(double noundef 1.0, double noundef 1.0)
+  ret double %next
+}
+define double @nextafter_can_constant_fold_with_nan_arg() {
+; CHECK-LABEL: define double @nextafter_can_constant_fold_with_nan_arg() {
+; CHECK-NEXT:    ret double 0x7FF8000000000000
+;
+  %arg = load double, double* @dbl_nan
+  %next = call double @nextafter(double 1.0, double %arg)
+  ret double %next
+}
+define double @nextafter_constant_fold_propagates_nan_payload() {
+; CHECK-LABEL: define double @nextafter_constant_fold_propagates_nan_payload() {
+; CHECK-NEXT:    ret double 0x7FF8000000000001
+;
+  %nan = load double, double* @dbl_nan
+  %tmp1 = bitcast double %nan to i64
+  %tmp2 = or i64 %tmp1, 1
+  %nan_with_payload = bitcast i64 %tmp2 to double
+  %next = call double @nextafter(double %nan_with_payload, double 1.0)
+  ret double %next
+}
+define double @nextafter_not_marked_dead_on_pos_overflow () {
+; CHECK-LABEL: define double @nextafter_not_marked_dead_on_pos_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nextafter(double 0x7FEFFFFFFFFFFFFF, double 0x7FF0000000000000)
+; CHECK-NEXT:    ret double 0x7FF0000000000000
+;
+  %arg1 = load double, double* @dbl_pos_max
+  %arg2 = load double, double* @dbl_pos_infinity
+  %next = call double @nextafter(double %arg1, double %arg2)
+  ret double %next
+}
+define double @nextafter_not_marked_dead_on_neg_overflow() {
+; CHECK-LABEL: define double @nextafter_not_marked_dead_on_neg_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nextafter(double 0xFFEFFFFFFFFFFFFF, double 0xFFF0000000000000)
+; CHECK-NEXT:    ret double 0xFFF0000000000000
+;
+  %arg1 = load double, double* @dbl_neg_max
+  %arg2 = load double, double* @dbl_neg_infinity
+  %next = call double @nextafter(double %arg1, double %arg2)
+  ret double %next
+}
+define double @nextafter_not_marked_dead_on_zero_from_above() {
+; CHECK-LABEL: define double @nextafter_not_marked_dead_on_zero_from_above() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nextafter(double 4.940660e-324, double 0.000000e+00)
+; CHECK-NEXT:    ret double 0.000000e+00
+;
+  %arg = load double, double* @dbl_pos_min_subnormal
+  %next = call double @nextafter(double %arg, double 0.0)
+  ret double %next
+}
+define double @nextafter_not_marked_dead_on_zero_from_below() {
+; CHECK-LABEL: define double @nextafter_not_marked_dead_on_zero_from_below() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nextafter(double -4.940660e-324, double 0.000000e+00)
+; CHECK-NEXT:    ret double -0.000000e+00
+;
+  %arg = load double, double* @dbl_neg_min_subnormal
+  %next = call double @nextafter(double %arg, double 0.0)
+  ret double %next
+}
+define double @nextafter_not_marked_dead_on_subnormal() {
+; CHECK-LABEL: define double @nextafter_not_marked_dead_on_subnormal() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nextafter(double 4.940660e-324, double 0x7FF0000000000000)
+; CHECK-NEXT:    ret double 9.881310e-324
+;
+  %subnormal = load double, double* @dbl_pos_min_subnormal
+  %infinity = load double, double* @dbl_pos_infinity
+  %next = call double @nextafter(double %subnormal, double %infinity)
+  ret double %next
+}
+
+define double @nextafter_not_marked_dead_on_poison() {
+; CHECK-LABEL: define double @nextafter_not_marked_dead_on_poison() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nextafter(double poison, double 1.000000e+00)
+; CHECK-NEXT:    ret double [[NEXT]]
+;
+  %next = call double @nextafter(double poison, double 1.0)
+  ret double %next
+}
+
+define double @nextafter_marked_dead_when_readnone() {
+; CHECK-LABEL: define double @nextafter_marked_dead_when_readnone() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nextafter(double 4.940660e-324, double 1.000000e+00) #[[ATTR1:[0-9]+]]
+; CHECK-NEXT:    ret double 9.881310e-324
+;
+  %subnormal = load double, double* @dbl_pos_min_subnormal
+  %next = call double @nextafter(double %subnormal, double 1.0) readnone
+  ret double %next
+}
+
+; ==================
+; nextafterf tests
+; ==================
+
+define float @nextafterf_can_constant_fold_up_direction() {
+; CHECK-LABEL: define float @nextafterf_can_constant_fold_up_direction() {
+; CHECK-NEXT:    ret float 0x3FF0000020000000
+;
+  %next = call float @nextafterf(float noundef 1.0, float noundef 2.0)
+  ret float %next
+}
+define float @nextafterf_can_constant_fold_down_direction() {
+; CHECK-LABEL: define float @nextafterf_can_constant_fold_down_direction() {
+; CHECK-NEXT:    ret float 0x3FEFFFFFE0000000
+;
+  %next = call float @nextafterf(float noundef 1.0, float noundef 0.0)
+  ret float %next
+}
+define float @nextafterf_can_constant_fold_equal_args() {
+; CHECK-LABEL: define float @nextafterf_can_constant_fold_equal_args() {
+; CHECK-NEXT:    ret float 1.000000e+00
+;
+  %next = call float @nextafterf(float noundef 1.0, float noundef 1.0)
+  ret float %next
+}
+define float @nextafterf_can_constant_fold_with_nan_arg() {
+; CHECK-LABEL: define float @nextafterf_can_constant_fold_with_nan_arg() {
+; CHECK-NEXT:    ret float 0x7FF8000000000000
+;
+  %arg = load float, float* @flt_nan
+  %next = call float @nextafterf(float 1.0, float %arg)
+  ret float %next
+}
+define float @nextafterf_constant_fold_propagates_nan_payload() {
+; CHECK-LABEL: define float @nextafterf_constant_fold_propagates_nan_payload() {
+; CHECK-NEXT:    ret float 0x7FF8000020000000
+;
+  %nan = load float, float* @flt_nan
+  %tmp1 = bitcast float %nan to i32
+  %tmp2 = or i32 %tmp1, 1
+  %nan_with_payload = bitcast i32 %tmp2 to float
+  %next = call float @nextafterf(float %nan_with_payload, float 1.0)
+  ret float %next
+}
+define float @nextafterf_not_marked_dead_on_pos_overflow() {
+; CHECK-LABEL: define float @nextafterf_not_marked_dead_on_pos_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nextafterf(float 0x47EFFFFFE0000000, float 0x7FF0000000000000)
+; CHECK-NEXT:    ret float 0x7FF0000000000000
+;
+  %arg1 = load float, float* @flt_pos_max
+  %arg2 = load float, float* @flt_pos_infinity
+  %next = call float @nextafterf(float %arg1, float %arg2)
+  ret float %next
+}
+define float @nextafterf_not_marked_dead_on_neg_overflow() {
+; CHECK-LABEL: define float @nextafterf_not_marked_dead_on_neg_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nextafterf(float 0xC7EFFFFFE0000000, float 0xFFF0000000000000)
+; CHECK-NEXT:    ret float 0xFFF0000000000000
+;
+  %arg1 = load float, float* @flt_neg_max
+  %arg2 = load float, float* @flt_neg_infinity
+  %next = call float @nextafterf(float %arg1, float %arg2)
+  ret float %next
+}
+define float @nextafterf_not_marked_dead_on_zero_from_above() {
+; CHECK-LABEL: define float @nextafterf_not_marked_dead_on_zero_from_above() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nextafterf(float 0x36A0000000000000, float 0.000000e+00)
+; CHECK-NEXT:    ret float 0.000000e+00
+;
+  %arg = load float, float* @flt_pos_min_subnormal
+  %next = call float @nextafterf(float %arg, float 0.0)
+  ret float %next
+}
+define float @nextafterf_not_marked_dead_on_zero_from_below() {
+; CHECK-LABEL: define float @nextafterf_not_marked_dead_on_zero_from_below() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nextafterf(float 0xB6A0000000000000, float 0.000000e+00)
+; CHECK-NEXT:    ret float -0.000000e+00
+;
+  %arg = load float, float* @flt_neg_min_subnormal
+  %next = call float @nextafterf(float %arg, float 0.0)
+  ret float %next
+}
+define float @nextafterf_not_marked_dead_on_subnormal() {
+; CHECK-LABEL: define float @nextafterf_not_marked_dead_on_subnormal() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nextafterf(float 0x36A0000000000000, float 0x7FF0000000000000)
+; CHECK-NEXT:    ret float 0x36B0000000000000
+;
+  %subnormal = load float, float* @flt_pos_min_subnormal
+  %infinity = load float, float* @flt_pos_infinity
+  %next = call float @nextafterf(float %subnormal, float %infinity)
+  ret float %next
+}
diff --git a/llvm/test/Transforms/InstCombine/constant-fold-nexttoward-fp128.ll b/llvm/test/Transforms/InstCombine/constant-fold-nexttoward-fp128.ll
new file mode 100644
index 0000000000000..dedf3e76a788e
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/constant-fold-nexttoward-fp128.ll
@@ -0,0 +1,211 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: cat %S/floating-point-constants.ll %s | opt -passes=instcombine -S | FileCheck %s
+
+declare double @nexttoward(double noundef, fp128 noundef) #0
+declare float @nexttowardf(float noundef, fp128 noundef) #0
+
+attributes #0 = { willreturn memory(errnomem: write) }
+
+; ==================
+; nexttoward tests
+; ==================
+
+define double @nexttoward_can_constant_fold_up_direction() {
+; CHECK-LABEL: define double @nexttoward_can_constant_fold_up_direction() {
+; CHECK-NEXT:    ret double 0x3FF0000000000001
+;
+  %arg = fpext double 2.0 to fp128
+  %next = call double @nexttoward(double noundef 1.0, fp128 %arg)
+  ret double %next
+}
+define double @nexttoward_can_constant_fold_down_direction() {
+; CHECK-LABEL: define double @nexttoward_can_constant_fold_down_direction() {
+; CHECK-NEXT:    ret double 0x3FEFFFFFFFFFFFFF
+;
+  %arg = fpext double 0.0 to fp128
+  %next = call double @nexttoward(double noundef 1.0, fp128 %arg)
+  ret double %next
+}
+define double @nexttoward_can_constant_fold_equal_args() {
+; CHECK-LABEL: define double @nexttoward_can_constant_fold_equal_args() {
+; CHECK-NEXT:    ret double 1.000000e+00
+;
+  %arg = fpext double 1.0 to fp128
+  %next = call double @nexttoward(double 1.0, fp128 %arg)
+  ret double %next
+}
+define double @nexttoward_can_constant_fold_with_nan_arg() {
+; CHECK-LABEL: define double @nexttoward_can_constant_fold_with_nan_arg() {
+; CHECK-NEXT:    ret double 0x7FF8000000000000
+;
+  %nan = load double, double* @dbl_nan
+  %arg = fpext double %nan to fp128
+  %next = call double @nexttoward(double 1.0, fp128 %arg)
+  ret double %next
+}
+define double @nexttoward_constant_fold_propagates_nan_payload() {
+; CHECK-LABEL: define double @nexttoward_constant_fold_propagates_nan_payload() {
+; CHECK-NEXT:    ret double 0x7FF8000000000001
+;
+  %nan = load double, double* @dbl_nan
+  %tmp1 = bitcast double %nan to i64
+  %tmp2 = or i64 %tmp1, 1
+  %nan_with_payload = bitcast i64 %tmp2 to double
+  %dummy_arg = fpext double 1.0 to fp128
+  %next = call double @nexttoward(double %nan_with_payload, fp128 %dummy_arg)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_pos_overflow() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_pos_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double 0x7FEFFFFFFFFFFFFF, fp128 0xL00000000000000007FFF000000000000)
+; CHECK-NEXT:    ret double 0x7FF0000000000000
+;
+  %pos_max = load double, double* @dbl_pos_max
+  %pos_inf = load double, double* @dbl_pos_infinity
+  %ext_pos_inf = fpext double %pos_inf to fp128
+  %next = call double @nexttoward(double %pos_max, fp128 %ext_pos_inf)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_neg_overflow() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_neg_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double 0xFFEFFFFFFFFFFFFF, fp128 0xL0000000000000000FFFF000000000000)
+; CHECK-NEXT:    ret double 0xFFF0000000000000
+;
+  %neg_max = load double, double* @dbl_neg_max
+  %neg_inf = load double, double* @dbl_neg_infinity
+  %ext_neg_inf = fpext double %neg_inf to fp128
+  %next = call double @nexttoward(double %neg_max, fp128 %ext_neg_inf)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_zero_from_above() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_zero_from_above() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double 4.940660e-324, fp128 0xL00000000000000000000000000000000)
+; CHECK-NEXT:    ret double 0.000000e+00
+;
+  %subnormal = load double, double* @dbl_pos_min_subnormal
+  %zero = fpext double 0.0 to fp128
+  %next = call double @nexttoward(double %subnormal, fp128 %zero)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_zero_from_below() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_zero_from_below() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double -4.940660e-324, fp128 0xL00000000000000000000000000000000)
+; CHECK-NEXT:    ret double -0.000000e+00
+;
+  %subnormal = load double, double* @dbl_neg_min_subnormal
+  %zero = fpext double 0.0 to fp128
+  %next = call double @nexttoward(double %subnormal, fp128 %zero)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_subnormal() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_subnormal() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double 4.940660e-324, fp128 0xL00000000000000003FFF000000000000)
+; CHECK-NEXT:    ret double 9.881310e-324
+;
+  %subnormal = load double, double* @dbl_pos_min_subnormal
+  %target = fpext double 1.0 to fp128
+  %next = call double @nexttoward(double %subnormal, fp128 %target)
+  ret double %next
+}
+
+; ==================
+; nexttowardf tests
+; ==================
+
+define float @nexttowardf_can_constant_fold_up_direction() {
+; CHECK-LABEL: define float @nexttowardf_can_constant_fold_up_direction() {
+; CHECK-NEXT:    ret float 0x3FF0000020000000
+;
+  %arg = fpext float 2.0 to fp128
+  %next = call float @nexttowardf(float noundef 1.0, fp128 %arg)
+  ret float %next
+}
+define float @nexttowardf_can_constant_fold_down_direction() {
+; CHECK-LABEL: define float @nexttowardf_can_constant_fold_down_direction() {
+; CHECK-NEXT:    ret float 0x3FEFFFFFE0000000
+;
+  %arg = fpext float 0.0 to fp128
+  %next = call float @nexttowardf(float noundef 1.0, fp128 %arg)
+  ret float %next
+}
+define float @nexttowardf_can_constant_fold_equal_args() {
+; CHECK-LABEL: define float @nexttowardf_can_constant_fold_equal_args() {
+; CHECK-NEXT:    ret float 1.000000e+00
+;
+  %arg = fpext float 1.0 to fp128
+  %next = call float @nexttowardf(float 1.0, fp128 %arg)
+  ret float %next
+}
+define float @nexttowardf_can_constant_fold_with_nan_arg() {
+; CHECK-LABEL: define float @nexttowardf_can_constant_fold_with_nan_arg() {
+; CHECK-NEXT:    ret float 0x7FF8000000000000
+;
+  %nan = load float, float* @flt_nan
+  %ext_nan = fpext float %nan to fp128
+  %next = call float @nexttowardf(float 1.0, fp128 %ext_nan)
+  ret float %next
+}
+define float @nexttowardf_constant_fold_propagates_nan_payload() {
+; CHECK-LABEL: define float @nexttowardf_constant_fold_propagates_nan_payload() {
+; CHECK-NEXT:    ret float 0x7FF8000020000000
+;
+  %nan = load float, float* @flt_nan
+  %tmp1 = bitcast float %nan to i32
+  %tmp2 = or i32 %tmp1, 1
+  %nan_with_payload = bitcast i32 %tmp2 to float
+  %dummy_arg = fpext float 1.0 to fp128
+  %next = call float @nexttowardf(float %nan_with_payload, fp128 %dummy_arg)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_pos_overflow () {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_pos_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0x47EFFFFFE0000000, fp128 0xL00000000000000007FFF000000000000)
+; CHECK-NEXT:    ret float 0x7FF0000000000000
+;
+  %pos_max = load float, float* @flt_pos_max
+  %pos_inf = load float, float* @flt_pos_infinity
+  %ext_pos_inf = fpext float %pos_inf to fp128
+  %next = call float @nexttowardf(float %pos_max, fp128 %ext_pos_inf)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_neg_overflow() {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_neg_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0xC7EFFFFFE0000000, fp128 0xL0000000000000000FFFF000000000000)
+; CHECK-NEXT:    ret float 0xFFF0000000000000
+;
+  %neg_max = load float, float* @flt_neg_max
+  %neg_inf = load float, float* @flt_neg_infinity
+  %ext_neg_inf = fpext float %neg_inf to fp128
+  %next = call float @nexttowardf(float %neg_max, fp128 %ext_neg_inf)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_zero_from_above() {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_zero_from_above() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0x36A0000000000000, fp128 0xL00000000000000000000000000000000)
+; CHECK-NEXT:    ret float 0.000000e+00
+;
+  %min_subnormal = load float, float* @flt_pos_min_subnormal
+  %zero = fpext float 0.0 to fp128
+  %next = call float @nexttowardf(float %min_subnormal, fp128 %zero)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_zero_from_below() {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_zero_from_below() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0xB6A0000000000000, fp128 0xL00000000000000000000000000000000)
+; CHECK-NEXT:    ret float -0.000000e+00
+;
+  %min_subnormal = load float, float* @flt_neg_min_subnormal
+  %zero = fpext float 0.0 to fp128
+  %next = call float @nexttowardf(float %min_subnormal, fp128 %zero)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_subnormal() {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_subnormal() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0x36A0000000000000, fp128 0xL00000000000000003FFF000000000000)
+; CHECK-NEXT:    ret float 0x36B0000000000000
+;
+  %subnormal = load float, float* @flt_pos_min_subnormal
+  %target = fpext float 1.0 to fp128
+  %next = call float @nexttowardf(float %subnormal, fp128 %target)
+  ret float %next
+}
diff --git a/llvm/test/Transforms/InstCombine/constant-fold-nexttoward-ppc-fp128.ll b/llvm/test/Transforms/InstCombine/constant-fold-nexttoward-ppc-fp128.ll
new file mode 100644
index 0000000000000..718e3333cefee
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/constant-fold-nexttoward-ppc-fp128.ll
@@ -0,0 +1,211 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: cat %S/floating-point-constants.ll %s | opt -passes=instcombine -S | FileCheck %s
+
+declare double @nexttoward(double noundef, ppc_fp128 noundef) #0
+declare float @nexttowardf(float noundef, ppc_fp128 noundef) #0
+
+attributes #0 = { willreturn memory(errnomem: write) }
+
+; ==================
+; nexttoward tests
+; ==================
+
+define double @nexttoward_can_constant_fold_up_direction() {
+; CHECK-LABEL: define double @nexttoward_can_constant_fold_up_direction() {
+; CHECK-NEXT:    ret double 0x3FF0000000000001
+;
+  %arg = fpext double 2.0 to ppc_fp128
+  %next = call double @nexttoward(double noundef 1.0, ppc_fp128 %arg)
+  ret double %next
+}
+define double @nexttoward_can_constant_fold_down_direction() {
+; CHECK-LABEL: define double @nexttoward_can_constant_fold_down_direction() {
+; CHECK-NEXT:    ret double 0x3FEFFFFFFFFFFFFF
+;
+  %arg = fpext double 0.0 to ppc_fp128
+  %next = call double @nexttoward(double noundef 1.0, ppc_fp128 %arg)
+  ret double %next
+}
+define double @nexttoward_can_constant_fold_equal_args() {
+; CHECK-LABEL: define double @nexttoward_can_constant_fold_equal_args() {
+; CHECK-NEXT:    ret double 1.000000e+00
+;
+  %arg = fpext double 1.0 to ppc_fp128
+  %next = call double @nexttoward(double 1.0, ppc_fp128 %arg)
+  ret double %next
+}
+define double @nexttoward_can_constant_fold_with_nan_arg() {
+; CHECK-LABEL: define double @nexttoward_can_constant_fold_with_nan_arg() {
+; CHECK-NEXT:    ret double 0x7FF8000000000000
+;
+  %nan = load double, double* @dbl_nan
+  %arg = fpext double %nan to ppc_fp128
+  %next = call double @nexttoward(double 1.0, ppc_fp128 %arg)
+  ret double %next
+}
+define double @nexttoward_constant_fold_propagates_nan_payload() {
+; CHECK-LABEL: define double @nexttoward_constant_fold_propagates_nan_payload() {
+; CHECK-NEXT:    ret double 0x7FF8000000000001
+;
+  %nan = load double, double* @dbl_nan
+  %tmp1 = bitcast double %nan to i64
+  %tmp2 = or i64 %tmp1, 1
+  %nan_with_payload = bitcast i64 %tmp2 to double
+  %dummy_arg = fpext double 1.0 to ppc_fp128
+  %next = call double @nexttoward(double %nan_with_payload, ppc_fp128 %dummy_arg)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_pos_overflow() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_pos_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double 0x7FEFFFFFFFFFFFFF, ppc_fp128 0xM7FF00000000000000000000000000000)
+; CHECK-NEXT:    ret double 0x7FF0000000000000
+;
+  %pos_max = load double, double* @dbl_pos_max
+  %pos_inf = load double, double* @dbl_pos_infinity
+  %ext_pos_inf = fpext double %pos_inf to ppc_fp128
+  %next = call double @nexttoward(double %pos_max, ppc_fp128 %ext_pos_inf)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_neg_overflow() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_neg_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double 0xFFEFFFFFFFFFFFFF, ppc_fp128 0xMFFF00000000000000000000000000000)
+; CHECK-NEXT:    ret double 0xFFF0000000000000
+;
+  %neg_max = load double, double* @dbl_neg_max
+  %neg_inf = load double, double* @dbl_neg_infinity
+  %ext_neg_inf = fpext double %neg_inf to ppc_fp128
+  %next = call double @nexttoward(double %neg_max, ppc_fp128 %ext_neg_inf)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_zero_from_above() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_zero_from_above() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double 4.940660e-324, ppc_fp128 0xM00000000000000000000000000000000)
+; CHECK-NEXT:    ret double 0.000000e+00
+;
+  %subnormal = load double, double* @dbl_pos_min_subnormal
+  %zero = fpext double 0.0 to ppc_fp128
+  %next = call double @nexttoward(double %subnormal, ppc_fp128 %zero)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_zero_from_below() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_zero_from_below() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double -4.940660e-324, ppc_fp128 0xM00000000000000000000000000000000)
+; CHECK-NEXT:    ret double -0.000000e+00
+;
+  %subnormal = load double, double* @dbl_neg_min_subnormal
+  %zero = fpext double 0.0 to ppc_fp128
+  %next = call double @nexttoward(double %subnormal, ppc_fp128 %zero)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_subnormal() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_subnormal() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double 4.940660e-324, ppc_fp128 0xM3FF00000000000000000000000000000)
+; CHECK-NEXT:    ret double 9.881310e-324
+;
+  %subnormal = load double, double* @dbl_pos_min_subnormal
+  %target = fpext double 1.0 to ppc_fp128
+  %next = call double @nexttoward(double %subnormal, ppc_fp128 %target)
+  ret double %next
+}
+
+; ==================
+; nexttowardf tests
+; ==================
+
+define float @nexttowardf_can_constant_fold_up_direction() {
+; CHECK-LABEL: define float @nexttowardf_can_constant_fold_up_direction() {
+; CHECK-NEXT:    ret float 0x3FF0000020000000
+;
+  %arg = fpext float 2.0 to ppc_fp128
+  %next = call float @nexttowardf(float noundef 1.0, ppc_fp128 %arg)
+  ret float %next
+}
+define float @nexttowardf_can_constant_fold_down_direction() {
+; CHECK-LABEL: define float @nexttowardf_can_constant_fold_down_direction() {
+; CHECK-NEXT:    ret float 0x3FEFFFFFE0000000
+;
+  %arg = fpext float 0.0 to ppc_fp128
+  %next = call float @nexttowardf(float noundef 1.0, ppc_fp128 %arg)
+  ret float %next
+}
+define float @nexttowardf_can_constant_fold_equal_args() {
+; CHECK-LABEL: define float @nexttowardf_can_constant_fold_equal_args() {
+; CHECK-NEXT:    ret float 1.000000e+00
+;
+  %arg = fpext float 1.0 to ppc_fp128
+  %next = call float @nexttowardf(float 1.0, ppc_fp128 %arg)
+  ret float %next
+}
+define float @nexttowardf_can_constant_fold_with_nan_arg() {
+; CHECK-LABEL: define float @nexttowardf_can_constant_fold_with_nan_arg() {
+; CHECK-NEXT:    ret float 0x7FF8000000000000
+;
+  %nan = load float, float* @flt_nan
+  %ext_nan = fpext float %nan to ppc_fp128
+  %next = call float @nexttowardf(float 1.0, ppc_fp128 %ext_nan)
+  ret float %next
+}
+define float @nexttowardf_constant_fold_propagates_nan_payload() {
+; CHECK-LABEL: define float @nexttowardf_constant_fold_propagates_nan_payload() {
+; CHECK-NEXT:    ret float 0x7FF8000020000000
+;
+  %nan = load float, float* @flt_nan
+  %tmp1 = bitcast float %nan to i32
+  %tmp2 = or i32 %tmp1, 1
+  %nan_with_payload = bitcast i32 %tmp2 to float
+  %dummy_arg = fpext float 1.0 to ppc_fp128
+  %next = call float @nexttowardf(float %nan_with_payload, ppc_fp128 %dummy_arg)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_pos_overflow () {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_pos_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0x47EFFFFFE0000000, ppc_fp128 0xM7FF00000000000000000000000000000)
+; CHECK-NEXT:    ret float 0x7FF0000000000000
+;
+  %pos_max = load float, float* @flt_pos_max
+  %pos_inf = load float, float* @flt_pos_infinity
+  %ext_pos_inf = fpext float %pos_inf to ppc_fp128
+  %next = call float @nexttowardf(float %pos_max, ppc_fp128 %ext_pos_inf)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_neg_overflow() {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_neg_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0xC7EFFFFFE0000000, ppc_fp128 0xMFFF00000000000000000000000000000)
+; CHECK-NEXT:    ret float 0xFFF0000000000000
+;
+  %neg_max = load float, float* @flt_neg_max
+  %neg_inf = load float, float* @flt_neg_infinity
+  %ext_neg_inf = fpext float %neg_inf to ppc_fp128
+  %next = call float @nexttowardf(float %neg_max, ppc_fp128 %ext_neg_inf)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_zero_from_above() {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_zero_from_above() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0x36A0000000000000, ppc_fp128 0xM00000000000000000000000000000000)
+; CHECK-NEXT:    ret float 0.000000e+00
+;
+  %min_subnormal = load float, float* @flt_pos_min_subnormal
+  %zero = fpext float 0.0 to ppc_fp128
+  %next = call float @nexttowardf(float %min_subnormal, ppc_fp128 %zero)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_zero_from_below() {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_zero_from_below() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0xB6A0000000000000, ppc_fp128 0xM00000000000000000000000000000000)
+; CHECK-NEXT:    ret float -0.000000e+00
+;
+  %min_subnormal = load float, float* @flt_neg_min_subnormal
+  %zero = fpext float 0.0 to ppc_fp128
+  %next = call float @nexttowardf(float %min_subnormal, ppc_fp128 %zero)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_subnormal() {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_subnormal() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0x36A0000000000000, ppc_fp128 0xM3FF00000000000000000000000000000)
+; CHECK-NEXT:    ret float 0x36B0000000000000
+;
+  %subnormal = load float, float* @flt_pos_min_subnormal
+  %target = fpext float 1.0 to ppc_fp128
+  %next = call float @nexttowardf(float %subnormal, ppc_fp128 %target)
+  ret float %next
+}
diff --git a/llvm/test/Transforms/InstCombine/constant-fold-nexttoward-x86-fp80.ll b/llvm/test/Transforms/InstCombine/constant-fold-nexttoward-x86-fp80.ll
new file mode 100644
index 0000000000000..590d0655f4009
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/constant-fold-nexttoward-x86-fp80.ll
@@ -0,0 +1,211 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: cat %S/floating-point-constants.ll %s | opt -passes=instcombine -S | FileCheck %s
+
+declare double @nexttoward(double noundef, x86_fp80 noundef) #0
+declare float @nexttowardf(float noundef, x86_fp80 noundef) #0
+
+attributes #0 = { willreturn memory(errnomem: write) }
+
+; ==================
+; nexttoward tests
+; ==================
+
+define double @nexttoward_can_constant_fold_up_direction() {
+; CHECK-LABEL: define double @nexttoward_can_constant_fold_up_direction() {
+; CHECK-NEXT:    ret double 0x3FF0000000000001
+;
+  %arg = fpext double 2.0 to x86_fp80
+  %next = call double @nexttoward(double noundef 1.0, x86_fp80 %arg)
+  ret double %next
+}
+define double @nexttoward_can_constant_fold_down_direction() {
+; CHECK-LABEL: define double @nexttoward_can_constant_fold_down_direction() {
+; CHECK-NEXT:    ret double 0x3FEFFFFFFFFFFFFF
+;
+  %arg = fpext double 0.0 to x86_fp80
+  %next = call double @nexttoward(double noundef 1.0, x86_fp80 %arg)
+  ret double %next
+}
+define double @nexttoward_can_constant_fold_equal_args() {
+; CHECK-LABEL: define double @nexttoward_can_constant_fold_equal_args() {
+; CHECK-NEXT:    ret double 1.000000e+00
+;
+  %arg = fpext double 1.0 to x86_fp80
+  %next = call double @nexttoward(double 1.0, x86_fp80 %arg)
+  ret double %next
+}
+define double @nexttoward_can_constant_fold_with_nan_arg() {
+; CHECK-LABEL: define double @nexttoward_can_constant_fold_with_nan_arg() {
+; CHECK-NEXT:    ret double 0x7FF8000000000000
+;
+  %nan = load double, double* @dbl_nan
+  %arg = fpext double %nan to x86_fp80
+  %next = call double @nexttoward(double 1.0, x86_fp80 %arg)
+  ret double %next
+}
+define double @nexttoward_constant_fold_propagates_nan_payload() {
+; CHECK-LABEL: define double @nexttoward_constant_fold_propagates_nan_payload() {
+; CHECK-NEXT:    ret double 0x7FF8000000000001
+;
+  %nan = load double, double* @dbl_nan
+  %tmp1 = bitcast double %nan to i64
+  %tmp2 = or i64 %tmp1, 1
+  %nan_with_payload = bitcast i64 %tmp2 to double
+  %dummy_arg = fpext double 1.0 to x86_fp80
+  %next = call double @nexttoward(double %nan_with_payload, x86_fp80 %dummy_arg)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_pos_overflow () {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_pos_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double 0x7FEFFFFFFFFFFFFF, x86_fp80 0xK7FFF8000000000000000)
+; CHECK-NEXT:    ret double 0x7FF0000000000000
+;
+  %pos_max = load double, double* @dbl_pos_max
+  %pos_inf = load double, double* @dbl_pos_infinity
+  %ext_pos_inf = fpext double %pos_inf to x86_fp80
+  %next = call double @nexttoward(double %pos_max, x86_fp80 %ext_pos_inf)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_neg_overflow() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_neg_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double 0xFFEFFFFFFFFFFFFF, x86_fp80 0xKFFFF8000000000000000)
+; CHECK-NEXT:    ret double 0xFFF0000000000000
+;
+  %neg_max = load double, double* @dbl_neg_max
+  %neg_inf = load double, double* @dbl_neg_infinity
+  %ext_neg_inf = fpext double %neg_inf to x86_fp80
+  %next = call double @nexttoward(double %neg_max, x86_fp80 %ext_neg_inf)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_zero_from_above() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_zero_from_above() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double 4.940660e-324, x86_fp80 0xK00000000000000000000)
+; CHECK-NEXT:    ret double 0.000000e+00
+;
+  %subnormal = load double, double* @dbl_pos_min_subnormal
+  %zero = fpext double 0.0 to x86_fp80
+  %next = call double @nexttoward(double %subnormal, x86_fp80 %zero)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_zero_from_below() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_zero_from_below() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double -4.940660e-324, x86_fp80 0xK00000000000000000000)
+; CHECK-NEXT:    ret double -0.000000e+00
+;
+  %subnormal = load double, double* @dbl_neg_min_subnormal
+  %zero = fpext double 0.0 to x86_fp80
+  %next = call double @nexttoward(double %subnormal, x86_fp80 %zero)
+  ret double %next
+}
+define double @nexttoward_not_marked_dead_on_subnormal() {
+; CHECK-LABEL: define double @nexttoward_not_marked_dead_on_subnormal() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call double @nexttoward(double 4.940660e-324, x86_fp80 0xK3FFF8000000000000000)
+; CHECK-NEXT:    ret double 9.881310e-324
+;
+  %subnormal = load double, double* @dbl_pos_min_subnormal
+  %target = fpext double 1.0 to x86_fp80
+  %next = call double @nexttoward(double %subnormal, x86_fp80 %target)
+  ret double %next
+}
+
+; ==================
+; nexttowardf tests
+; ==================
+
+define float @nexttowardf_can_constant_fold_up_direction() {
+; CHECK-LABEL: define float @nexttowardf_can_constant_fold_up_direction() {
+; CHECK-NEXT:    ret float 0x3FF0000020000000
+;
+  %arg = fpext float 2.0 to x86_fp80
+  %next = call float @nexttowardf(float noundef 1.0, x86_fp80 %arg)
+  ret float %next
+}
+define float @nexttowardf_can_constant_fold_down_direction() {
+; CHECK-LABEL: define float @nexttowardf_can_constant_fold_down_direction() {
+; CHECK-NEXT:    ret float 0x3FEFFFFFE0000000
+;
+  %arg = fpext float 0.0 to x86_fp80
+  %next = call float @nexttowardf(float noundef 1.0, x86_fp80 %arg)
+  ret float %next
+}
+define float @nexttowardf_can_constant_fold_equal_args() {
+; CHECK-LABEL: define float @nexttowardf_can_constant_fold_equal_args() {
+; CHECK-NEXT:    ret float 1.000000e+00
+;
+  %arg = fpext float 1.0 to x86_fp80
+  %next = call float @nexttowardf(float 1.0, x86_fp80 %arg)
+  ret float %next
+}
+define float @nexttowardf_can_constant_fold_with_nan_arg() {
+; CHECK-LABEL: define float @nexttowardf_can_constant_fold_with_nan_arg() {
+; CHECK-NEXT:    ret float 0x7FF8000000000000
+;
+  %nan = load float, float* @flt_nan
+  %ext_nan = fpext float %nan to x86_fp80
+  %next = call float @nexttowardf(float 1.0, x86_fp80 %ext_nan)
+  ret float %next
+}
+define float @nexttowardf_constant_fold_propagates_nan_payload() {
+; CHECK-LABEL: define float @nexttowardf_constant_fold_propagates_nan_payload() {
+; CHECK-NEXT:    ret float 0x7FF8000020000000
+;
+  %nan = load float, float* @flt_nan
+  %tmp1 = bitcast float %nan to i32
+  %tmp2 = or i32 %tmp1, 1
+  %nan_with_payload = bitcast i32 %tmp2 to float
+  %dummy_arg = fpext float 1.0 to x86_fp80
+  %next = call float @nexttowardf(float %nan_with_payload, x86_fp80 %dummy_arg)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_pos_overflow() {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_pos_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0x47EFFFFFE0000000, x86_fp80 0xK7FFF8000000000000000)
+; CHECK-NEXT:    ret float 0x7FF0000000000000
+;
+  %pos_max = load float, float* @flt_pos_max
+  %pos_inf = load float, float* @flt_pos_infinity
+  %ext_pos_inf = fpext float %pos_inf to x86_fp80
+  %next = call float @nexttowardf(float %pos_max, x86_fp80 %ext_pos_inf)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_neg_overflow() {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_neg_overflow() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0xC7EFFFFFE0000000, x86_fp80 0xKFFFF8000000000000000)
+; CHECK-NEXT:    ret float 0xFFF0000000000000
+;
+  %neg_max = load float, float* @flt_neg_max
+  %neg_inf = load float, float* @flt_neg_infinity
+  %ext_neg_inf = fpext float %neg_inf to x86_fp80
+  %next = call float @nexttowardf(float %neg_max, x86_fp80 %ext_neg_inf)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_zero_from_above() {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_zero_from_above() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0x36A0000000000000, x86_fp80 0xK00000000000000000000)
+; CHECK-NEXT:    ret float 0.000000e+00
+;
+  %min_subnormal = load float, float* @flt_pos_min_subnormal
+  %zero = fpext float 0.0 to x86_fp80
+  %next = call float @nexttowardf(float %min_subnormal, x86_fp80 %zero)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_zero_from_below() {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_zero_from_below() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0xB6A0000000000000, x86_fp80 0xK00000000000000000000)
+; CHECK-NEXT:    ret float -0.000000e+00
+;
+  %min_subnormal = load float, float* @flt_neg_min_subnormal
+  %zero = fpext float 0.0 to x86_fp80
+  %next = call float @nexttowardf(float %min_subnormal, x86_fp80 %zero)
+  ret float %next
+}
+define float @nexttowardf_not_marked_dead_on_subnormal() {
+; CHECK-LABEL: define float @nexttowardf_not_marked_dead_on_subnormal() {
+; CHECK-NEXT:    [[NEXT:%.*]] = call float @nexttowardf(float 0x36A0000000000000, x86_fp80 0xK3FFF8000000000000000)
+; CHECK-NEXT:    ret float 0x36B0000000000000
+;
+  %subnormal = load float, float* @flt_pos_min_subnormal
+  %target = fpext float 1.0 to x86_fp80
+  %next = call float @nexttowardf(float %subnormal, x86_fp80 %target)
+  ret float %next
+}
diff --git a/llvm/test/Transforms/InstCombine/floating-point-constants.ll b/llvm/test/Transforms/InstCombine/floating-point-constants.ll
new file mode 100644
index 0000000000000..5d135b0aaebaa
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/floating-point-constants.ll
@@ -0,0 +1,48 @@
+; RUN: true
+; Constants for edge case float testing.
+
+; Generated with:
+; clang -S -emit-llvm floating-point-constants.c
+;
+; // floating-point-constants.c
+; #include <math.h>
+; #include <float.h>
+;
+; const float flt_nan = NAN;
+; const float flt_pos_min_subnormal = FLT_TRUE_MIN;
+; const float flt_pos_min_normal = FLT_MIN;
+; const float flt_pos_max = FLT_MAX;
+; const float flt_pos_infinity = INFINITY;
+; const float flt_neg_min_subnormal = -FLT_TRUE_MIN;
+; const float flt_neg_min_normal = -FLT_MIN;
+; const float flt_neg_max = -FLT_MAX;
+; const float flt_neg_infinity = -INFINITY;
+;
+; const double dbl_nan = NAN;
+; const double dbl_pos_min_subnormal = DBL_TRUE_MIN;
+; const double dbl_pos_min_normal = DBL_MIN;
+; const double dbl_pos_max = DBL_MAX;
+; const double dbl_pos_infinity = INFINITY;
+; const double dbl_neg_min_subnormal = -DBL_TRUE_MIN;
+; const double dbl_neg_min_normal = -DBL_MIN;
+; const double dbl_neg_max = -DBL_MAX;
+; const double dbl_neg_infinity = -INFINITY;
+
+@flt_nan = dso_local constant float 0x7FF8000000000000, align 4
+@flt_pos_min_subnormal = dso_local constant float 0x36A0000000000000, align 4
+@flt_pos_min_normal = dso_local constant float 0x3810000000000000, align 4
+@flt_pos_max = dso_local constant float 0x47EFFFFFE0000000, align 4
+@flt_pos_infinity = dso_local constant float 0x7FF0000000000000, align 4
+@flt_neg_min_subnormal = dso_local constant float 0xB6A0000000000000, align 4
+@flt_neg_min_normal = dso_local constant float 0xB810000000000000, align 4
+@flt_neg_max = dso_local constant float 0xC7EFFFFFE0000000, align 4
+@flt_neg_infinity = dso_local constant float 0xFFF0000000000000, align 4
+@dbl_nan = dso_local constant double 0x7FF8000000000000, align 8
+@dbl_pos_min_subnormal = dso_local constant double 4.940660e-324, align 8
+@dbl_pos_min_normal = dso_local constant double 0x10000000000000, align 8
+@dbl_pos_max = dso_local constant double 0x7FEFFFFFFFFFFFFF, align 8
+@dbl_pos_infinity = dso_local constant double 0x7FF0000000000000, align 8
+@dbl_neg_min_subnormal = dso_local constant double -4.940660e-324, align 8
+@dbl_neg_min_normal = dso_local constant double 0x8010000000000000, align 8
+@dbl_neg_max = dso_local constant double 0xFFEFFFFFFFFFFFFF, align 8
+@dbl_neg_infinity = dso_local constant double 0xFFF0000000000000, align 8
diff --git a/llvm/unittests/ADT/APFloatTest.cpp b/llvm/unittests/ADT/APFloatTest.cpp
index 99cc38b6b422b..a6fe35e66684c 100644
--- a/llvm/unittests/ADT/APFloatTest.cpp
+++ b/llvm/unittests/ADT/APFloatTest.cpp
@@ -10182,4 +10182,30 @@ TEST(APFloatTest, FrexpQuietSNaN) {
   EXPECT_FALSE(Result.isSignaling());
 }
 
+TEST(APFloatTest, getPromoted) {
+  // Strengthening promotions are allowed.
+  APFloat ValidPromotionTest(1.0f);
+  APFloat DoubleVal = ValidPromotionTest.getPromoted(APFloat::IEEEdouble());
+
+  // Trivial promotions to the same semantics are allowed.
+  DoubleVal.getPromoted(DoubleVal.getSemantics());
+
+  // Promotions have the expected semantics and preserve the initial value.
+  EXPECT_EQ(&DoubleVal.getSemantics(), &APFloat::IEEEdouble());
+  EXPECT_EQ(1.0, DoubleVal.convertToDouble());
+
+#if defined(GTEST_HAS_DEATH_TEST) && !defined(NDEBUG)
+  // All invalid promotions are swiftly killed.
+  APFloat InvalidPromotionTest =
+      ValidPromotionTest.getPromoted(APFloat::IEEEquad());
+  EXPECT_DEATH(InvalidPromotionTest.getPromoted(APFloat::IEEEdouble()),
+               "Target semantics will lose information");
+  EXPECT_DEATH(InvalidPromotionTest.getPromoted(APFloat::x87DoubleExtended()),
+               "Target semantics will lose information");
+  EXPECT_DEATH(
+      InvalidPromotionTest.getPromoted(APFloat::PPCDoubleDoubleLegacy()),
+      "Target semantics will lose information");
+#endif
+}
+
 } // namespace