diff --git a/src/tools/run-make-support/src/rustdoc.rs b/src/tools/run-make-support/src/rustdoc.rs
index c4f4e9f9bd23..9c77f1ca4624 100644
--- a/src/tools/run-make-support/src/rustdoc.rs
+++ b/src/tools/run-make-support/src/rustdoc.rs
@@ -151,6 +151,13 @@ pub fn library_search_path<P: AsRef<Path>>(&mut self, path: P) -> &mut Self {
         self
     }
 
+    /// Specify the output format.
+    pub fn output_format(&mut self, format: &str) -> &mut Self {
+        self.cmd.arg("--output-format");
+        self.cmd.arg(format);
+        self
+    }
+
     #[track_caller]
     pub fn run_fail_assert_exit_code(&mut self, code: i32) -> Output {
         let caller_location = std::panic::Location::caller();