Build Post-LLVM Install

"Note that once both LLVM and Clang have been configured *and built*
it is not necessary to perform a top-level make to rebuild changes
made only to LLDB."
http://lldb.llvm.org/build.html#BuildingLldbOnLinux

I'm getting the feeling that even if LLVM and CLang are both
*installed*, you still have to unpack the LLDB source in
LLVM-src/tools.
I obviously can't "./configure" lldb, and trying to cmake lldb alone
starts with a "No cmake_minimum_required command is present" failure
and then even fixing that it continues going downhill.

But if I do place lldb in ./llvm/tools, then "./configure" and make,
it will error with:
"make[1]: Entering directory '/home/user/Desktop/llvm/tools/lldb/lib'
/bin/sh: 1: /home/user/Desktop/llvm/Release/bin/llvm-config: not found
/home/user/Desktop/llvm/Makefile.rules:1077: *** llvm-config --libs
failed. Stop."
But "llvm-config" was installed in "/usr/local/bin". Why would it look in llvm?

My expectation: build llvm alone, then build clang alone, then build lldb alone.