Reading the AST from the bitcode generated by clang

Hi all,
After reading the documentation on clang I still have the following
question:
How do I read the bitcode generated by clang from a C++ file? I need to
have all the AST information in memory.

Thanks,
Sitvanit

Sitvanit Ruah
Formal Verification Group
IBM Haifa Research Laboratory
Tel: 972-4-828-1249