diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index daeca43169d4a..f117bafce6527 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -1112,7 +1112,9 @@ fn get_backend_from_raw_matches(
     matches: &Matches,
 ) -> Box<dyn CodegenBackend> {
     let debug_flags = matches.opt_strs("Z");
-    let backend_name = debug_flags.iter().find_map(|x| x.strip_prefix("codegen-backend="));
+    let backend_name = debug_flags.iter().find_map(|x| {
+        x.strip_prefix("codegen-backend=").or(x.strip_prefix("codegen_backend="))
+    });
     let target = parse_target_triple(early_dcx, matches);
     let sysroot = filesearch::materialize_sysroot(matches.opt_str("sysroot").map(PathBuf::from));
     let target = config::build_target_config(early_dcx, &target, &sysroot);