diff --git a/llvm/.gitignore b/llvm/.gitignore
--- a/llvm/.gitignore
+++ b/llvm/.gitignore
@@ -65,6 +65,8 @@
 tools/lld
 # llgo, which is tracked independently.
 tools/llgo
+# MLIR, which is tracked independently.
+tools/mlir
 # Polly, which is tracked independently.
 tools/polly
 # avrlit, which is tracked independently.