After a developer builds LLDB from source on Windows (assuming they've built it with Python support enabled), they may be somewhat flustered when it fails to launch with a cryptic error.
This happens because Windows can't find python27.dll (or python27_d.dll in case LLDB was built in debug mode). Many developers may have previously installed a release build of Python 2.7 and will not notice anything is amiss when they run a release build of LLDB because Windows will load the python27.dll from one of the system directories or PATH (rather than the one that the LLDB build instructions tell them to build). The issue tends to be more pronounced with debug builds of LLDB, since fewer developers probably have python27_d.dll sitting in one of the Windows system directories.
To ensure Windows loads the correct custom built Python DLL when launching LLDB I've added a post-build event that copies the relevant DLL (based on the LLDB build configuration) from PYTHON_HOME to the directory in which the LLDB executable is generated.