I have an AD group called SQLAdmin. I have set SQLAdmin up in this way:

SQLAdmin - Browser, Content Manager, My Reports, Publisher, Report Builder

 

I have set up System Roles like this:

System Administrator

Execute

Manage (jobs, server properties, server security, roles, shared schedules)

 

System User

Execute

View (report server properties, shared schedules)

 

I have a user in the SQLAdmin group who does not see the 'Report Builder' link. I am not a system admin, but I am in the SQLAdmin group as well, and I do see the 'Report Builder' link.