problem llvm2.9

Hi all
I had build llvm 2.8 on my Linux system, when i run "opt -version " command , it shows llvm2.8.
I want replace llvm 2.8 with 2.9, i used “rpm -qa llvm” and “make unistall” and “make clean” and then build llvm 2.9 but when run “opt -version” i get llvm 2.8 yet. and when want use “opt” i get error.
how can i replace llvm 2.8 with 2.9?