Extracting the name of the RDL from an SSRS report

We have several published SSRS reports in our organisation that haven't been documented properly; they're in use but we don't know when they were created or what the original requirements were. We need to make some changes to some of them, but the names that show in SSRS are useless. Ideally I'd like to find out the name of the associated RDL so that I can find it in our source control repository, but I can't see any way to extract it from SSRS. Anyone ever managed to do this?

Thanks...