LDAP WP Conversion of Users

I am curious if WPMUdev or someone out there in the community knows of a plugin that is reliable to use with other databases in userid imports to MU. The idea being that the home DB userid and password would be linked to the WP userid and password allowing the end user to simply use their “home database (DB)” login to gain access to their WP Website and not have to use multiple logins. I was looking at the Synchronization plugin but it doesn’t seem to do what I am asking for.