diff --git a/src/test/run-pass/issue-4120.rs b/src/test/run-pass/issue-4120.rs
index 16946f32e311..82bd48c4aa08 100644
--- a/src/test/run-pass/issue-4120.rs
+++ b/src/test/run-pass/issue-4120.rs
@@ -1,3 +1,7 @@
+// xfail-test
+
+// XFAIL'd due to Valgrind complaining about TLS loss.
+
 // Copyright 2013 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.