Markdown sample doesn't build?

When I try to build, from the build output I see:

cp ..../MarkdownViewer/sundown/bin/Debug/libsundown.dylib: No such file or directory

---------------------- Done ----------------------

Custom command failed (exit code: 1) Build canceled.

So then I try building the libsundown project explicitly, and I get:

Building: libsundown (Debug)

Performing main compilation...

Precompiling headers

Compiling source to object files

gcc -MMD "..../MarkdownViewer/sundown/autolink.c" -g -Wall -Werror -O3 -n -fPIC -Wall -Werror -Wsign-compare -std=c99 -m32

-I"..../MarkdownViewer/sundown/obj/Debug/prec/Debug" -c -o "..../MarkdownViewer/sundown/bin/Debug/autolink.o"

clang: error: argument unused during compilation: '-n'

Build complete -- 1 error, 0 warnings

---------------------- Done ----------------------

Build: 1 error, 0 warnings