How do you solve unintended dependencies, that are in the path you have to include? For example, when building postgresql on OSX, it always links against libpq

How do you solve unintended dependencies, that are in the path you have to include? For example, when building postgresql on OSX, it always links against libpq.dylib in /usr/lib, not against the one it just built. In theory, it could be possible to exclude /usr/lib from the -L path, but then I would lose other libraries, that ship with the system (i.e. libz, libxml2, libxslt, libpam, libSystem). The other possibility is to build all these dependencies too - except libSystem... Right now I'm using install_name_tool to fix the binary, but that is an ugly hack. (The other problem in this case is, that system libpq is x64-only. It means that i386 build would fail).