If you look at the documentation for the -X functions, the -l test is described as:

File is a symbolic link (false if symlinks aren't supported by the file system).

If you look at the Alphabetical Listing of Perl Functions section of perlport, the following note is listed under -X:

(Win32, VMS, RISC OS) -g , -k , -l , -u , -A are not particularly meaningful.

Based on those documents, it looks like -l is not going to work on Windows.

I'm not saying this is the best alternative, but one alternative that you could consider is the testL function from the Win32::LongPath module.