Multiple Installations with shared core files

I’m basically trying to install wordpress to multiple domains on my hosting. Thing is, it takes awhile to transfer the files multiple times, and they take up a file amount limit that my hosting has. So, the sites won’t be the same exact thing. I know how to have them use the same database with prefixes, but not to share common files, like core files, etc. It should only be the theme files and possibly plugins that would need to be different file-wise. Any way to store them on one domain and link the others to that spot?

Thanks.