diff --git a/test/lit.site.cfg.in b/test/lit.site.cfg.in
index ae387f5..7a786a3 100644
--- a/test/lit.site.cfg.in
+++ b/test/lit.site.cfg.in
@@ -60,3 +60,6 @@
 configuration = libcxxabi.test.config.Configuration(lit_config, config)
 configuration.configure()
 configuration.print_config_info()
+
+lit_config.warning("This is a legacy testing configuration which will be removed in LLVM 16. "
+                   "Please use one of the configurations in libcxxabi/test/configs or define your own.")