diff --git a/rustfmt.toml b/rustfmt.toml
new file mode 100644
index 00000000000..df230cde9b7
--- /dev/null
+++ b/rustfmt.toml
@@ -0,0 +1,6 @@
+# Currently, most of the code in the compiler uses historical style.
+#
+# For new code, consider running rustfmt with this config (it should
+# be picked up automatically).
+version = "Two"
+use_small_heuristics = "Max"