diff --git a/llvm/include/llvm/IR/Function.h b/llvm/include/llvm/IR/Function.h
index 955a4fca6f86f..6ac768b51395c 100644
--- a/llvm/include/llvm/IR/Function.h
+++ b/llvm/include/llvm/IR/Function.h
@@ -48,9 +48,11 @@ class AssemblyAnnotationWriter;
 class Constant;
 struct DenormalMode;
 class DISubprogram;
+enum LibFunc : unsigned;
 class LLVMContext;
 class Module;
 class raw_ostream;
+class TargetLibraryInfoImpl;
 class Type;
 class User;
 class BranchProbabilityInfo;
@@ -120,6 +122,15 @@ class LLVM_EXTERNAL_VISIBILITY Function : public GlobalObject,
   void setIsNewDbgInfoFormat(bool NewVal);
 
 private:
+  friend class TargetLibraryInfoImpl;
+
+  static constexpr LibFunc UnknownLibFunc = LibFunc(-1);
+
+  /// Cache for TLI::getLibFunc() result without prototype validation.
+  /// UnknownLibFunc if uninitialized. NotLibFunc if definitely not lib func.
+  /// Otherwise may be libfunc if prototype validation passes.
+  mutable LibFunc LibFuncCache = UnknownLibFunc;
+
   void CheckLazyArguments() const {
     if (hasLazyArguments())
       BuildLazyArguments();
@@ -239,12 +250,11 @@ class LLVM_EXTERNAL_VISIBILITY Function : public GlobalObject,
 
   static Intrinsic::ID lookupIntrinsicID(StringRef Name);
 
-  /// Recalculate the ID for this function if it is an Intrinsic defined
-  /// in llvm/Intrinsics.h.  Sets the intrinsic ID to Intrinsic::not_intrinsic
-  /// if the name of this function does not match an intrinsic in that header.
+  /// Update internal caches that depend on the function name (such as the
+  /// intrinsic ID and libcall cache).
   /// Note, this method does not need to be called directly, as it is called
   /// from Value::setName() whenever the name of this function changes.
-  void recalculateIntrinsicID();
+  void updateAfterNameChange();
 
   /// getCallingConv()/setCallingConv(CC) - These method get and set the
   /// calling convention of this function.  The enum values for the known
diff --git a/llvm/lib/Analysis/TargetLibraryInfo.cpp b/llvm/lib/Analysis/TargetLibraryInfo.cpp
index 7b38583e9bc75..20959cf6948f6 100644
--- a/llvm/lib/Analysis/TargetLibraryInfo.cpp
+++ b/llvm/lib/Analysis/TargetLibraryInfo.cpp
@@ -1138,8 +1138,15 @@ bool TargetLibraryInfoImpl::getLibFunc(const Function &FDecl,
   const Module *M = FDecl.getParent();
   assert(M && "Expecting FDecl to be connected to a Module.");
 
-  return getLibFunc(FDecl.getName(), F) &&
-         isValidProtoForLibFunc(*FDecl.getFunctionType(), F, *M);
+  if (FDecl.LibFuncCache == Function::UnknownLibFunc)
+    if (!getLibFunc(FDecl.getName(), FDecl.LibFuncCache))
+      FDecl.LibFuncCache = NotLibFunc;
+
+  if (FDecl.LibFuncCache == NotLibFunc)
+    return false;
+
+  F = FDecl.LibFuncCache;
+  return isValidProtoForLibFunc(*FDecl.getFunctionType(), F, *M);
 }
 
 void TargetLibraryInfoImpl::disableAllFunctions() {
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index 49e0c1c5883c2..c3706dc1b02fc 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -912,7 +912,8 @@ Intrinsic::ID Function::lookupIntrinsicID(StringRef Name) {
                                                      : Intrinsic::not_intrinsic;
 }
 
-void Function::recalculateIntrinsicID() {
+void Function::updateAfterNameChange() {
+  LibFuncCache = UnknownLibFunc;
   StringRef Name = getName();
   if (!Name.startswith("llvm.")) {
     HasLLVMReservedName = false;
diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index c05f9ac5a0fe0..b6e25c46b514d 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -377,7 +377,7 @@ void Value::setNameImpl(const Twine &NewName) {
 void Value::setName(const Twine &NewName) {
   setNameImpl(NewName);
   if (Function *F = dyn_cast<Function>(this))
-    F->recalculateIntrinsicID();
+    F->updateAfterNameChange();
 }
 
 void Value::takeName(Value *V) {