diff --git a/clang/lib/AST/Interp/ByteCodeEmitter.cpp b/clang/lib/AST/Interp/ByteCodeEmitter.cpp
index a3d4c7d7392da..fee4432a8f661 100644
--- a/clang/lib/AST/Interp/ByteCodeEmitter.cpp
+++ b/clang/lib/AST/Interp/ByteCodeEmitter.cpp
@@ -27,7 +27,8 @@ using namespace clang::interp;
 /// Similar information is available via ASTContext::BuiltinInfo,
 /// but that is not correct for our use cases.
 static bool isUnevaluatedBuiltin(unsigned BuiltinID) {
-  return BuiltinID == Builtin::BI__builtin_classify_type;
+  return BuiltinID == Builtin::BI__builtin_classify_type ||
+         BuiltinID == Builtin::BI__builtin_os_log_format_buffer_size;
 }
 
 Function *ByteCodeEmitter::compileFunc(const FunctionDecl *FuncDecl) {
diff --git a/clang/test/CodeGen/builtins.c b/clang/test/CodeGen/builtins.c
index b41efb59e61db..1f998236501d2 100644
--- a/clang/test/CodeGen/builtins.c
+++ b/clang/test/CodeGen/builtins.c
@@ -1,6 +1,7 @@
 // RUN: %clang_cc1 -emit-llvm -o %t %s
 // RUN: not grep __builtin %t
 // RUN: %clang_cc1 -emit-llvm -triple x86_64-darwin-apple -o - %s | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -triple x86_64-darwin-apple -fexperimental-new-constant-interpreter -o - %s | FileCheck %s
 
 int printf(const char *, ...);