I’ve run into what appears to be an odd bug with the autoconf-based build when run in a path containing spaces:
LLVM_SRC_ROOT := $(call realpath, /path/with some/spaces)
in Makefile.config returns empty string, while:
LLVM_SRC_ROOT := $(call realpath, /path/without/spaces)
returns the expected “/path/without/spaces”.
This breaks the build from the very start.
(This is on Ubuntu 11.10.)