I know I can search svn logs using svn log --search $pattern. However, I'd like to limit the results to a certain number. The only thing I was able to find is the -l option but it limits the original log entries on which the search is run and I'd like for the search to be run on the entire log history and only limit the number of results themselves.
There is no built-in way to tell svn log --search to limit the results. As you already know, you can limit the number of revisions it checks, but this is not what you look for. I guess that you could write a script that checks the output of svn log and cuts it to the necessary amount. Don't forget that you could use --xml switch.
If you desperately need such feature by some reason, drop a line to users@ Apache Subversion mailing list. Describe how and why you need this enhancement and maybe it will be filed as a feature request. :)