Bitter Melon the cat says, paste a C/C++ program in the text box or upload one from your computer, and you can see the equivalent LLVM code, meow!!
If you want to upload a file from a program with header files, you should preprocess it (e.g., with the -save-temps or -E options to gcc) first.
If you have questions about the LLVM code generated by the front-end, please check the FAQ (e.g., what is this __main thing?). If the FAQ does not address it, please send an email to the llvmdev mailing list.
Note that the generated LLVM code will be easier to read if you use stdio (e.g., printf) than iostreams (e.g., std::cout).