diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index d05f1a3f34b78..46458bd3d5809 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -951,8 +951,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         (default: PLT is disabled if full relro is enabled)"),
     polonius: bool = (false, parse_bool, [UNTRACKED],
         "enable polonius-based borrow-checker (default: no)"),
-    polymorphize: bool = (false, parse_bool, [TRACKED],
-          "perform polymorphization analysis"),
+    polymorphize: bool = (true, parse_bool, [TRACKED],
+        "perform polymorphization analysis"),
     pre_link_arg: (/* redirected to pre_link_args */) = ((), parse_string_push, [UNTRACKED],
         "a single extra argument to prepend the linker invocation (can be used several times)"),
     pre_link_args: Vec<String> = (Vec::new(), parse_list, [UNTRACKED],