diff --git a/llvm/lib/Transforms/Scalar/SCCP.cpp b/llvm/lib/Transforms/Scalar/SCCP.cpp
index c8d7c4de37fc0..0551120daece7 100644
--- a/llvm/lib/Transforms/Scalar/SCCP.cpp
+++ b/llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -28,6 +28,7 @@
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/Analysis/GlobalsModRef.h"
+#include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/ValueLattice.h"
 #include "llvm/Analysis/ValueLatticeUtils.h"
@@ -369,8 +370,10 @@ class SCCPSolver : public InstVisitor<SCCPSolver> {
   // markConstant - Make a value be marked as "constant".  If the value
   // is not already a constant, add it to the instruction work list so that
   // the users of the instruction are updated later.
-  bool markConstant(ValueLatticeElement &IV, Value *V, Constant *C) {
-    if (!IV.markConstant(C)) return false;
+  bool markConstant(ValueLatticeElement &IV, Value *V, Constant *C,
+                    bool MayIncludeUndef = false) {
+    if (!IV.markConstant(C, MayIncludeUndef))
+      return false;
     LLVM_DEBUG(dbgs() << "markConstant: " << *C << ": " << *V << '\n');
     pushToWorkList(IV, V);
     return true;
@@ -954,23 +957,33 @@ void SCCPSolver::visitBinaryOperator(Instruction &I) {
   if (V1State.isOverdefined() && V2State.isOverdefined())
     return (void)markOverdefined(&I);
 
-  // Both operands are non-integer constants or constant expressions.
+  // If either of the operands is a constant, try to fold it to a constant.
   // TODO: Use information from notconstant better.
-  if (isConstant(V1State) && isConstant(V2State)) {
-    Constant *C = ConstantExpr::get(I.getOpcode(), getConstant(V1State),
-                                    getConstant(V2State));
-    // X op Y -> undef.
-    if (isa<UndefValue>(C))
-      return;
-    return (void)markConstant(IV, &I, C);
+  if ((V1State.isConstant() || V2State.isConstant())) {
+    Value *V1 = isConstant(V1State) ? getConstant(V1State) : I.getOperand(0);
+    Value *V2 = isConstant(V2State) ? getConstant(V2State) : I.getOperand(1);
+    Value *R = SimplifyBinOp(I.getOpcode(), V1, V2, SimplifyQuery(DL));
+    auto *C = dyn_cast_or_null<Constant>(R);
+    if (C) {
+      // X op Y -> undef.
+      if (isa<UndefValue>(C))
+        return;
+      // Conservatively assume that the result may be based on operands that may
+      // be undef. Note that we use mergeInValue to combine the constant with
+      // the existing lattice value for I, as different constants might be found
+      // after one of the operands go to overdefined, e.g. due to one operand
+      // being a special floating value.
+      ValueLatticeElement NewV;
+      NewV.markConstant(C, /*MayIncludeUndef=*/true);
+      return (void)mergeInValue(&I, NewV);
+    }
   }
 
   // Only use ranges for binary operators on integers.
   if (!I.getType()->isIntegerTy())
     return markOverdefined(&I);
 
-  // Operands are either constant ranges, notconstant, overdefined or one of the
-  // operands is a constant.
+  // Try to simplify to a constant range.
   ConstantRange A = ConstantRange::getFull(I.getType()->getScalarSizeInBits());
   ConstantRange B = ConstantRange::getFull(I.getType()->getScalarSizeInBits());
   if (V1State.isConstantRange())
diff --git a/llvm/test/Transforms/SCCP/float-nan-simplification.ll b/llvm/test/Transforms/SCCP/float-nan-simplification.ll
new file mode 100644
index 0000000000000..1cedbaa69e44a
--- /dev/null
+++ b/llvm/test/Transforms/SCCP/float-nan-simplification.ll
@@ -0,0 +1,67 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -sccp -S %s | FileCheck %s
+
+; When marking the edge from bb2 -> exit as executable first, %p will be NaN
+; first and %v.1 will simplify to NaN. But when marking bb1 -> exit executable,
+; %p will we overdefined and %v.1 will be simplified to 0.0. Make sure we go to
+; overdefined, instead of crashing.
+; TODO: Can we do better, i.e. choose the 'conservative' 0.0 initially?
+define float @test1(float %a, i1 %bc) {
+; CHECK-LABEL: @test1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[BC:%.*]], label [[BB1:%.*]], label [[BB2:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    br label [[EXIT:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[P:%.*]] = phi float [ [[A:%.*]], [[BB1]] ], [ 0x7FF8000000000000, [[BB2]] ]
+; CHECK-NEXT:    [[V_1:%.*]] = fmul float [[P]], 0.000000e+00
+; CHECK-NEXT:    [[V_2:%.*]] = fadd float [[V_1]], 0xFFF8000000000000
+; CHECK-NEXT:    ret float [[V_2]]
+;
+entry:
+  br i1 %bc, label %bb1, label %bb2
+
+bb1:
+  br label %exit
+
+bb2:
+  br label %exit
+
+exit:
+  %p = phi float [ %a, %bb1 ], [ 0x7FF8000000000000, %bb2 ]
+  %v.1 = fmul float %p, 0.000000e+00
+  %v.2 = fadd float %v.1, 0xFFF8000000000000
+  ret float %v.2
+}
+
+; Same as @test1, but with the incoming values switched.
+define float @test2(float %a, i1 %bc) {
+; CHECK-LABEL: @test2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[BC:%.*]], label [[BB1:%.*]], label [[BB2:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    br label [[EXIT:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[P:%.*]] = phi float [ 0x7FF8000000000000, [[BB1]] ], [ [[A:%.*]], [[BB2]] ]
+; CHECK-NEXT:    [[V_1:%.*]] = fmul float [[P]], 0.000000e+00
+; CHECK-NEXT:    ret float 0xFFF8000000000000
+;
+entry:
+  br i1 %bc, label %bb1, label %bb2
+
+bb1:
+  br label %exit
+
+bb2:
+  br label %exit
+
+exit:
+  %p = phi float [ 0x7FF8000000000000, %bb1 ], [ %a, %bb2 ]
+  %v.1 = fmul float %p, 0.000000e+00
+  %v.2 = fadd float %v.1, 0xFFF8000000000000
+  ret float %v.2
+}
diff --git a/llvm/test/Transforms/SCCP/ub-shift.ll b/llvm/test/Transforms/SCCP/ub-shift.ll
index 6e15d6b2bccdc..fbcaef422870e 100644
--- a/llvm/test/Transforms/SCCP/ub-shift.ll
+++ b/llvm/test/Transforms/SCCP/ub-shift.ll
@@ -3,10 +3,8 @@
 
 define void @shift_undef_64(i64* %p) {
 ; CHECK-LABEL: @shift_undef_64(
-; CHECK-NEXT:    [[R1:%.*]] = lshr i64 -1, 4294967296
-; CHECK-NEXT:    store i64 [[R1]], i64* [[P:%.*]]
-; CHECK-NEXT:    [[R2:%.*]] = ashr i64 -1, 4294967297
-; CHECK-NEXT:    store i64 [[R2]], i64* [[P]]
+; CHECK-NEXT:    store i64 0, i64* [[P:%.*]]
+; CHECK-NEXT:    store i64 -1, i64* [[P]]
 ; CHECK-NEXT:    [[R3:%.*]] = shl i64 -1, 4294967298
 ; CHECK-NEXT:    store i64 [[R3]], i64* [[P]]
 ; CHECK-NEXT:    ret void
@@ -25,10 +23,8 @@ define void @shift_undef_64(i64* %p) {
 
 define void @shift_undef_65(i65* %p) {
 ; CHECK-LABEL: @shift_undef_65(
-; CHECK-NEXT:    [[R1:%.*]] = lshr i65 2, -18446744073709551615
-; CHECK-NEXT:    store i65 [[R1]], i65* [[P:%.*]]
-; CHECK-NEXT:    [[R2:%.*]] = ashr i65 4, -18446744073709551615
-; CHECK-NEXT:    store i65 [[R2]], i65* [[P]]
+; CHECK-NEXT:    store i65 0, i65* [[P:%.*]]
+; CHECK-NEXT:    store i65 0, i65* [[P]]
 ; CHECK-NEXT:    [[R3:%.*]] = shl i65 1, -18446744073709551615
 ; CHECK-NEXT:    store i65 [[R3]], i65* [[P]]
 ; CHECK-NEXT:    ret void
@@ -47,10 +43,8 @@ define void @shift_undef_65(i65* %p) {
 
 define void @shift_undef_256(i256* %p) {
 ; CHECK-LABEL: @shift_undef_256(
-; CHECK-NEXT:    [[R1:%.*]] = lshr i256 2, 18446744073709551617
-; CHECK-NEXT:    store i256 [[R1]], i256* [[P:%.*]]
-; CHECK-NEXT:    [[R2:%.*]] = ashr i256 4, 18446744073709551618
-; CHECK-NEXT:    store i256 [[R2]], i256* [[P]]
+; CHECK-NEXT:    store i256 0, i256* [[P:%.*]]
+; CHECK-NEXT:    store i256 0, i256* [[P]]
 ; CHECK-NEXT:    [[R3:%.*]] = shl i256 1, 18446744073709551619
 ; CHECK-NEXT:    store i256 [[R3]], i256* [[P]]
 ; CHECK-NEXT:    ret void
@@ -69,10 +63,8 @@ define void @shift_undef_256(i256* %p) {
 
 define void @shift_undef_511(i511* %p) {
 ; CHECK-LABEL: @shift_undef_511(
-; CHECK-NEXT:    [[R1:%.*]] = lshr i511 -1, 1208925819614629174706276
-; CHECK-NEXT:    store i511 [[R1]], i511* [[P:%.*]]
-; CHECK-NEXT:    [[R2:%.*]] = ashr i511 -2, 1208925819614629174706200
-; CHECK-NEXT:    store i511 [[R2]], i511* [[P]]
+; CHECK-NEXT:    store i511 0, i511* [[P:%.*]]
+; CHECK-NEXT:    store i511 -1, i511* [[P]]
 ; CHECK-NEXT:    [[R3:%.*]] = shl i511 -3, 1208925819614629174706180
 ; CHECK-NEXT:    store i511 [[R3]], i511* [[P]]
 ; CHECK-NEXT:    ret void
diff --git a/llvm/test/Transforms/SCCP/vector-bitcast.ll b/llvm/test/Transforms/SCCP/vector-bitcast.ll
index 35312034c65b8..b032085083c60 100644
--- a/llvm/test/Transforms/SCCP/vector-bitcast.ll
+++ b/llvm/test/Transforms/SCCP/vector-bitcast.ll
@@ -2,8 +2,7 @@
 
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32-S128"
 
-; FIXME: Add back support for handling special values of vector/fp types.
-; CHECK: store volatile <2 x i64> %and.i119.i, <2 x i64>* %p
+; CHECK: store volatile <2 x i64> zeroinitializer, <2 x i64>* %p
 ; rdar://11324230
 
 define void @foo(<2 x i64>* %p) nounwind {