Software Without a Build System?

Does anyone have any experience developing medium or large projects (I don't view "LOC" as all that meaningful but I'm assuming at least 100k and a lot of files.) that purposefully don't use a build systems of any kind for the primary source distribution?

I'm not talking about systems that don't use any build system at all. (I consider those projects to be cruel.) I'm talking about those libraries that distribute huge "single shot" files (possibly files already run through a variant of "CPP") or have layouts with "master" files that include everything (using the actual include directive) as the primary source distribution.

I'm looking for comments from developers who've actually interacted with clients of such projects.

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If you don't need the context for why I'm here, don't bother to read any further. You will only waste your time.
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I had been thinking of setting up a minimal version of the build system I wrote years ago so that a user could "g++ -c combined_source.cxx -o kmakey.exe", or whatever, so that the interdependence "bootstrap" dance can be eliminated.

I quickly realized that it was an idiotic step because my library only barely needs the build system facilities that are unique. I decided to remove the dependance entirely by moving some of the important bits into the library source tree and killing off the build system. (I've only ever used it for this one thing.) I kind of still liked the idea of not needing a build system which would work even better with just the library.
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I'm working on the 2012 rewrite of my library. I've done a good job decoupling the old (2008) version from the build system over the years. It used to take a couple of hours to build my library on my development machine. It was such a complicated mess because of all the interdependence. It was gross and that will be avoided in the updated version.
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Pinkie Pie!

^ Only here because you deserve a pony if you got this far. ^
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Soma