With most Linux developers relying upon GDB as their debugger of choice and the Apple-employed LLVM developers mostly working on OS X and iOS, the LLVM Debugger (LLDB) hasn't traditionally grown too much in functionality outside the Apple world. Fortunately, in recent months LLDB has become more diverse with the support expanding to better serve Linux, Windows, and BSD developers.
LLDB reuses LLVM Clang for adapting to the latest C/C++ code, uses the MJIT dynamic execution engine for expression evaluation, the LLVM disassembler, and can also use Clang's AST parser while being easily adaptable to other LLVM-based projects. This design of LLDB and extensively reusing the other LLVM components has made it quite attractive while being more portable to developers and more efficient than other debuggers for non-standard cases.
For those curious about this LLVM debugger, on Friday there was an LLVM blog posting about LLDB 3.3 and its debugging future. More details on the open-source debugger itself can be found on the LLDB project page.