I worked around it the other day by

1. forking
2. Setting execution time limit in the child with BSD::Resource
3. writing result to a temporary file
4. in the parent, wait for the child and read the temp file

This is rather messy (and probably not very secure because the handling of temporary files is tricky). And I couldn't find a sandbox executer on cpan :(

BTW I needed that mess for an evalbot for #perl6.