diff --git a/llvm/include/llvm/IR/Function.h b/llvm/include/llvm/IR/Function.h
index 2b4ce6d7a1b0..7fe58cf7ff5a 100644
--- a/llvm/include/llvm/IR/Function.h
+++ b/llvm/include/llvm/IR/Function.h
@@ -137,7 +137,13 @@ public:
   /// The particular intrinsic functions which correspond to this value are
   /// defined in llvm/Intrinsics.h.
   Intrinsic::ID getIntrinsicID() const LLVM_READONLY { return IntID; }
-  bool isIntrinsic() const { return getName().startswith("llvm."); }
+  bool isIntrinsic() const {
+    // Intrinsic::not_intrinsic must be 0.
+    return IntID != 0;
+  }
+  /// Return true if the function's name starts with "llvm.".  All intrinsics
+  /// have this prefix.
+  bool hasLLVMReservedName() const { return getName().startswith("llvm."); }
 
   /// \brief Recalculate the ID for this function if it is an Intrinsic defined
   /// in llvm/Intrinsics.h.  Sets the intrinsic ID to Intrinsic::not_intrinsic
diff --git a/llvm/lib/CodeGen/WinEHPrepare.cpp b/llvm/lib/CodeGen/WinEHPrepare.cpp
index 041fb7b912bf..28efee085819 100644
--- a/llvm/lib/CodeGen/WinEHPrepare.cpp
+++ b/llvm/lib/CodeGen/WinEHPrepare.cpp
@@ -949,10 +949,14 @@ void WinEHPrepare::removeImplausibleInstructions(Function &F) {
           continue;
 
         // Skip call sites which are nounwind intrinsics or inline asm.
+        //
+        // FIXME: Should this check isIntrinsic() instead of
+        // hasLLVMReservedName?  The latter is conservative.
         auto *CalledFn =
             dyn_cast<Function>(CS.getCalledValue()->stripPointerCasts());
-        if (CalledFn && ((CalledFn->isIntrinsic() && CS.doesNotThrow()) ||
-                         CS.isInlineAsm()))
+        if (CalledFn &&
+            ((CalledFn->hasLLVMReservedName() && CS.doesNotThrow()) ||
+             CS.isInlineAsm()))
           continue;
 
         // This call site was not part of this funclet, remove it.
diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index 9b2399dd880c..bf5cc187e867 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -905,7 +905,7 @@ void SlotTracker::processInstructionMetadata(const Instruction &I) {
   // Process metadata used directly by intrinsics.
   if (const CallInst *CI = dyn_cast<CallInst>(&I))
     if (Function *F = CI->getCalledFunction())
-      if (F->isIntrinsic())
+      if (F->hasLLVMReservedName())
         for (auto &Op : I.operands())
           if (auto *V = dyn_cast_or_null<MetadataAsValue>(Op))
             if (MDNode *N = dyn_cast<MDNode>(V->getMetadata()))
@@ -3378,7 +3378,7 @@ void Type::print(raw_ostream &OS, bool /*IsForDebug*/, bool NoDetails) const {
 static bool isReferencingMDNode(const Instruction &I) {
   if (const auto *CI = dyn_cast<CallInst>(&I))
     if (Function *F = CI->getCalledFunction())
-      if (F->isIntrinsic())
+      if (F->hasLLVMReservedName())
         for (auto &Op : I.operands())
           if (auto *V = dyn_cast_or_null<MetadataAsValue>(Op))
             if (isa<MDNode>(V->getMetadata()))
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index e1223d0d0337..d9c59241ddf4 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -488,9 +488,7 @@ static ArrayRef<const char *> findTargetSubtable(StringRef Name) {
 
 /// \brief This does the actual lookup of an intrinsic ID which
 /// matches the given function name.
-static Intrinsic::ID lookupIntrinsicID(const ValueName *ValName) {
-  StringRef Name = ValName->getKey();
-
+static Intrinsic::ID lookupIntrinsicID(StringRef Name) {
   ArrayRef<const char *> NameTable = findTargetSubtable(Name);
   int Idx = Intrinsic::lookupLLVMIntrinsicByName(NameTable, Name);
   if (Idx == -1)
@@ -508,12 +506,11 @@ static Intrinsic::ID lookupIntrinsicID(const ValueName *ValName) {
 }
 
 void Function::recalculateIntrinsicID() {
-  const ValueName *ValName = this->getValueName();
-  if (!ValName || !isIntrinsic()) {
+  if (!hasLLVMReservedName()) {
     IntID = Intrinsic::not_intrinsic;
     return;
   }
-  IntID = lookupIntrinsicID(ValName);
+  IntID = lookupIntrinsicID(getName());
 }
 
 /// Returns a stable mangling for the type specified for use in the name
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 682e934d4b0f..659a22428e2c 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -3647,7 +3647,7 @@ void Verifier::visitInstruction(Instruction &I) {
       // Check to make sure that the "address of" an intrinsic function is never
       // taken.
       Assert(
-          !F->isIntrinsic() ||
+          !F->hasLLVMReservedName() ||
               i == (isa<CallInst>(I) ? e - 1 : isa<InvokeInst>(I) ? e - 3 : 0),
           "Cannot take the address of an intrinsic!", &I);
       Assert(