You have many object files and your linking line for a program in your OS grows longer and longer? GNU AR helps.
It creates archives of object files alongside with a table of the symbols, which each object file (==member) sports.
USAGE: ar -rcs archive.a obj_fil1.o obj_fil2.o obj_fil3.o obj_fil4.o ... obj_filN.o
You link your program's object file against crt0.o and the archive.a file.
Important: If you link other object files besides the library archive.a, take care that the archive.a is right behind these object files (or have it be the very last file in the list of files to link) - so the linker can resolve the one or other occurrence of a symbol which is covered by some member of the archive.a library.
See also the 
GNU 'ar' online manual.