URL aliases is supported in Drupal by help of pathauto module; if you enable the Token module, you can use it efficiently by using tokens. Once these modules are enabled, you can visit admin/config/search/path/patterns to set the patterns for URLs.
But as I see in your question, you are looking to set this for menu; you can't do that here.
There is logic behind it for not supporting it. Suppose you have a node/18 for about-us and you have two menu 'About-Us" & "About-Company". Now you can add this same node/18 to both places as child.
How can you have two URL aliases for single node/18? So this is the reason why menu are not supported I think.
You can go for creating content type & use pattern for that. You can set pattern for taxonomy, users, etc.