diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -420,6 +420,10 @@
     setValueName(V->getValueName());
     V->setValueName(nullptr);
     getValueName()->setValue(this);
+    if (Function *F = dyn_cast<Function>(V))
+      F->recalculateIntrinsicID();
+    if (Function *F = dyn_cast<Function>(this))
+      F->recalculateIntrinsicID();
     return;
   }
 
@@ -432,6 +436,11 @@
   V->setValueName(nullptr);
   getValueName()->setValue(this);
 
+  if (Function *F = dyn_cast<Function>(V))
+    F->recalculateIntrinsicID();
+  if (Function *F = dyn_cast<Function>(this))
+    F->recalculateIntrinsicID();
+
   if (ST)
     ST->reinsertValue(this);
 }
diff --git a/llvm/unittests/IR/ValueTest.cpp b/llvm/unittests/IR/ValueTest.cpp
--- a/llvm/unittests/IR/ValueTest.cpp
+++ b/llvm/unittests/IR/ValueTest.cpp
@@ -312,4 +312,48 @@
   ASSERT_TRUE(ExitDbg->getValue(0) == cast<Value>(B));
   ASSERT_TRUE(Ret->getOperand(0) == cast<Value>(B));
 }
+
+TEST(ValueTest, IntrinsicFunctionNames) {
+  LLVMContext C;
+  const char *ModuleString = "declare void @llvm.foo(i32)\n";
+
+  SMDiagnostic Err;
+  std::unique_ptr<Module> M = parseAssemblyString(ModuleString, Err, C);
+
+  // Any function beginning with "llvm." has an LLVM-reserved name and is
+  // considered an intrinsic.
+  Function *F = M->getFunction("llvm.foo");
+  EXPECT_TRUE(F->isIntrinsic());
+
+  // Create an intrinsic function explicitly. Check that it is indeed an
+  // intrinsic.
+  auto *FTy = F->getFunctionType();
+  auto *F1 = Function::Create(FTy, GlobalValue::ExternalLinkage, "llvm.foo", *M);
+  EXPECT_TRUE(F1->isIntrinsic());
+
+  // Create a new non-intrinsic function. Set the name from a known intrinsic -
+  // this should become an intrinsic. The old function should still be an
+  // intrinsic.
+  auto *F2 = Function::Create(FTy, GlobalValue::ExternalLinkage, "bar", *M);
+  F2->setName(F1->getName());
+  EXPECT_TRUE(F2->isIntrinsic());
+  EXPECT_TRUE(F1->isIntrinsic());
+
+  // Create a new non-intrinsic function. *Take* the name from an intrinsic -
+  // this should become be an intrinsic. The old function should no longer be
+  // an intrinsic.
+  auto *F3 = Function::Create(FTy, GlobalValue::ExternalLinkage, "baz", *M);
+  F3->takeName(F);
+  EXPECT_FALSE(F->isIntrinsic());
+  EXPECT_TRUE(F3->isIntrinsic());
+
+  F->setName("baz");
+  EXPECT_FALSE(F->isIntrinsic());
+
+  // Have an intrinsic take the name of a non-intrinsic and neither are
+  // intrinsics afterwards.
+  F3->takeName(F);
+  EXPECT_FALSE(F3->isIntrinsic());
+  EXPECT_FALSE(F->isIntrinsic());
+}
 } // end anonymous namespace