diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4660,6 +4660,7 @@
   // cleanup.
   if (!C.isForDiagnostics())
     CmdArgs.push_back("-disable-free");
+  CmdArgs.push_back("-clear-ast-before-backend");
 
 #ifdef NDEBUG
   const bool IsAssertBuild = false;
diff --git a/clang/lib/Interpreter/Interpreter.cpp b/clang/lib/Interpreter/Interpreter.cpp
--- a/clang/lib/Interpreter/Interpreter.cpp
+++ b/clang/lib/Interpreter/Interpreter.cpp
@@ -113,6 +113,10 @@
 
   Clang->getTarget().adjust(Clang->getDiagnostics(), Clang->getLangOpts());
 
+  // Don't clear the AST before backend codegen since we do codegen multiple
+  // times, reusing the same AST.
+  Clang->getCodeGenOpts().ClearASTBeforeBackend = false;
+
   return std::move(Clang);
 }