EDIT 2018/05/15: This can be achieved with a meta tag; please add that tag to your index.html and disregard this post.
This is not a complete answer to the question (for the technical answer please refer to @Zze's answer above), but there's an important step that needs to be added:
COMPATIBILITY MODE
Even with the appropriate polyfills in place, there are still issues with running Angular 2+ apps using the polyfills on IE11. If you are running the site off an intranet host (ie. if you are testing it at http://localhost or another mapped local domain name), you must go into Compatibility View settings and uncheck "Display intranet sites in Compatibility View", since IE11's Compatibility View breaks a couple of the conventions included in the ES5 polyfills for Angular.