The dynamic libraries that tbb builds on OS X are missing the install_name, current_version and compatibility_version. These should be specified at build time. (Where you already use the -dynamiclib flag, add the -install_name, -current_version and -compatibility_version flags with the appropriate values.) The install_name should be the absolute path where the library will be found after installation. For example, if libtbb.dylib will ultimately be installed at /usr/local/lib/libtbb.dylib, then at build time its install_name should be set to /usr/local/lib/libtbb.dylib. This means there will need to be a way (variable?) for the user invoking the build system to inform it what the final install prefix will be.
I guess you need to add this to LIB_LINK_FLAGS variable in build/macos.*.inc files. we can't put -install_name with absolute path since many people use these libraries in different places. and I suggest to look at -rpath parameter.