Go to the Likes page on your timeline. Click the Edit button in the upper right. Privacy visibility buttons will pop up next to each Like category for you to change the visibility of Likes. Make sure to scroll down to the bottom so you don't miss the last category "Other Pages You Like."
Yes, Facebook intentionally doesn't do a good job of advertising this. For me, though, I'm satisfied that the option is there (and that my option to stalk my friends is there as well).