diff --git a/cc/pgo.go b/cc/pgo.go
index 9363916..7334ea2 100644
--- a/cc/pgo.go
+++ b/cc/pgo.go
@@ -27,8 +27,11 @@
 
 var (
 	// Add flags to ignore warnings that profiles are old or missing for
-	// some functions
-	profileUseOtherFlags = []string{"-Wno-backend-plugin"}
+	// some functions, and turn on the experimental new pass manager.
+	profileUseOtherFlags = []string{
+		"-Wno-backend-plugin",
+		"-fexperimental-new-pass-manager",
+	}
 
 	globalPgoProfileProjects = []string{
 		"toolchain/pgo-profiles",