Check out the branch you want to pull Master branch into, in this case the branch is roles:

git checkout roles

Then rebase the branch by running:

git rebase -i origin/Master

Squash commits, modify commit messages, etc as needed. Then, before you force push back to roles branch, ensure the rebase happened smoothly by running your code and make sure things still look right. Then force push:

git push -f origin roles

Now your branch has brought in Master branch, and then reapplied your changes, then pushed back up. This is ideal before filing a merge request, as conflicts should now be minimized.