Compiling with -Wall

I just finished a blog post about a nasal demon I encountered while working on our game:

In the last paragraph I explained that UBT does not use the -Wall equivalent of Visual Studio under Windows. Is there any way to enable this easily, or do we have to modify UBT ourselves to do this? What was the reason this was disabled (or just not enabled)? It would save me a lot of headahces in the future.