Pruning branches that were deleted in upstream Git repo but still exist in my fork

I created a fork of a git repo on BitBucket (let's call it `fork_origin`). Now the upstream repository (let's call it `upstream_origin`) has had numerous branches merged into it's master and deleted. So running ``` git fetch --prune upstream_origin ``` deleted lots of `remote/upstream_origin/` branches, but now those same branches still exist in the `remote/fork_origin/` namespace. Is there a standard git command to deal with this? I'd like to stay away from complex bash scripts that do mass deletes on the remote repos. UPDATE: As suggested, I tried to use the remote prune command: ``` git remote prune fork_origin ``` However, it had no effect. Upon further investigation, that seems to work only for 'stale' branches, but when I run: ``` git remote show fork_origin ``` it shows that all of the branches are still 'tracked'. So it makes sense that the `git remote prune` command had nothing stale to delete. Is there a way to force the remote repo (`fork_origin`) to update it's branch statuses relative to `upstream_origin`?