Does a new master cylinder need to be primed before the system can be bled out?

yes, new masters need to be bench bled. You'll need a bleeding kit, they sell em in the help aisle, or just a couple short peices of brakeline that will go itno the ports in the master. Bend em up and around so they are in the flkuid in the reservoirs (submersed completely) then stroke the master till she bubbles no more.

Take your time bench bleeding the M/C.To fast and you will aerate the Dot 3.If you are not a flat rate tech..grab a sandwich and a coke and then bleed it one more time after letting it sit.Give it a good gravity bleed also before pumping the pedal.

You may have a hard time finding MC bench bleed kits. I looked in like 4 different auto chains and couldn't find them. Why? I learned that most MCs come with the kit, so they quit selling them separately. The MC I just put in two months ago showed up in the mail, with bleeder kit.