diff --git a/lib/CodeGen/BackendUtil.cpp b/lib/CodeGen/BackendUtil.cpp
index 1cbc69b..1707ec5 100644
--- a/lib/CodeGen/BackendUtil.cpp
+++ b/lib/CodeGen/BackendUtil.cpp
@@ -247,6 +247,7 @@
   }
 
   std::vector<const char *> BackendArgs;
+  BackendArgs.reserve(16);
   BackendArgs.push_back("clang"); // Fake program name.
   if (!CodeGenOpts.DebugPass.empty()) {
     BackendArgs.push_back("-debug-pass");