diff --git a/build/moz.configure/rust.configure b/build/moz.configure/rust.configure
index 90bb9dc67495..5744b4c80dd5 100644
--- a/build/moz.configure/rust.configure
+++ b/build/moz.configure/rust.configure
@@ -240,3 +240,10 @@ set_config('RUSTC_COMMIT', depends(rustc_info)(lambda i: i.commit))
 # Until we remove all the other Rust checks in old-configure.
 add_old_configure_assignment('RUSTC', rustc)
 add_old_configure_assignment('RUST_TARGET', rust_target_triple)
+
+# This option is separate from --enable-tests because Rust tests are particularly
+# expensive in terms of compile time (especially for code in libxul).
+option('--enable-rust-tests',
+       help='Enable building of Rust tests, and build-time execution of them')
+
+set_config('MOZ_RUST_TESTS', depends('--enable-rust-tests')(lambda v: bool(v)))