How do I use relative path in links

Hi I’m in the process of transferring my wordpress site to HostGator and currently have a temporary url for the site. I’ve changed the site url in the wp_options table and in settings>general. But the links in the posts and pages have my old site hardcoded, so my question is rather than going thru my site changing every link to the temporary url and then change it back again once I transfer the domain, is there a way to specify a relative path or if not a plugin to change all the url’s in 1 operation?

Thanks for any help

David