$ cat t.llbuild 
client:
  name: basic
  version: 0

targets:
  "": ["foo-stat"]

commands:
  C1:
    tool: shell
    outputs: ["foo"]
    args: ln -sf does/not/exist foo

  C2:
    tool: shell
    inputs: ["foo"]
    outputs: ["foo-stat"]
    args: stat -s foo | tee foo-stat

$ llbuild buildsystem build -f t.llbuild 
/bin/sh -c "ln -sf does/not/exist foo"
/bin/sh -c "stat -s foo | tee foo-stat"
st_dev=16777225 st_ino=14250438 st_mode=0120755 st_nlink=1 st_uid=501 st_gid=0 st_rdev=0 st_size=14 st_atime=1453531949 st_mtime=1453531949 st_ctime=1453531949 st_birthtime=1453531949 st_blksize=4096 st_blocks=8 st_flags=0

$ llbuild buildsystem build -f t.llbuild 
/bin/sh -c "ln -sf does/not/exist foo"