diff --git a/tools/cpp/empty_main.c b/tools/cpp/empty_main.c
new file mode 100644
index 0000000..79996de
--- /dev/null
+++ b/tools/cpp/empty_main.c
@@ -0,0 +1,3 @@
+// Used by //tools/build_rules:empty_main.bzl.
+
+int main() {}