diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp
--- a/clang/lib/CodeGen/CGExprConstant.cpp
+++ b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -1122,9 +1122,10 @@
     }
 
     case CK_AtomicToNonAtomic:
-    case CK_NonAtomicToAtomic:
-    case CK_NoOp:
     case CK_ConstructorConversion:
+    case CK_FunctionToPointerDecay:
+    case CK_NoOp:
+    case CK_NonAtomicToAtomic:
       return Visit(subExpr, destType);
 
     case CK_ArrayToPointerDecay:
@@ -1189,7 +1190,6 @@
     case CK_CPointerToObjCPointerCast:
     case CK_BlockPointerToObjCPointerCast:
     case CK_AnyPointerToBlockPointerCast:
-    case CK_FunctionToPointerDecay:
     case CK_BaseToDerived:
     case CK_DerivedToBase:
     case CK_UncheckedDerivedToBase:
@@ -1241,6 +1241,13 @@
     return llvm::ConstantInt::get(CGM.getLLVMContext(), I->getValue());
   }
 
+  llvm::Constant *VisitDeclRefExpr(DeclRefExpr *D, QualType T) {
+    ValueDecl *VD = D->getDecl();
+    if (isa<FunctionDecl>(VD))
+      return CGM.getModule().getNamedValue(VD->getName());
+    return nullptr;
+  }
+
   llvm::Constant *EmitArrayInitialization(InitListExpr *ILE, QualType T) {
     auto *CAT = CGM.getContext().getAsConstantArrayType(ILE->getType());
     assert(CAT && "can't emit array init for non-constant-bound array");