NTFS permission change when migrating to new Domain

We have a Netapps san that we use as a file share.

We are migrating to another supposed trusted domain in our AD structure

They will shut down our existing domain.

Are there any tools that anyone is aware of that will map existing NTFS

permissions either by user or groups and convert or add permissions for the

new domain. I am sure there has to be some to help do this rather than me

trying to go to our fileshare server and manually click on all folders and

reset the permissions. This would take days.

Thanks in advance, for any help!