Rotation issue: How to print slides, 4-per-page, using CUPS lp

I am trying to print 4-slides per page using CUPS lp (in landscape). However, the pages do not emerge rotated no matter what I do. (It looks terrible!) I get the same result whether: 1. I use CUPS to rotate, -o orientation-requested=4 2. if I use pdf90 to rotate, pdf90 --suffix 'foo' file.pdf 3. if I do nothing. Here is the code I use: lp -o fit-to-page -o number-up=4 -o number-up-layout="btlr" -o page-border="single-thick" -o sides=two-sided-short-edge file.pdf