[js][web] error running tests/web/prepare_test_libs.py

Questions
1

I have a question about the ./tests/web/prepare_test_libs.py after following all these steps:
https://github.com/dmlc/tvm/blob/master/web/README.md

I ran prepare_test_libs.py and got the following output:

Traceback (most recent call last):
  File "./tests/web/prepare_test_libs.py", line 21, in <module>
    prepare_test_libs(os.path.join(curr_path, "../../lib"))
  File "./tests/web/prepare_test_libs.py", line 9, in prepare_test_libs
    raise RuntimeError("Target %s is not enbaled" % target)
RuntimeError: Target llvm -target=asmjs-unknown-emscripten -system-lib is not enbaled

What can I do to fix this?
Can I use a different target?
If so can how can I get a list of targets?

llc --version:

LLVM (http://llvm.org/):
  LLVM version 6.0.1
  Optimized build.
  Default target: x86_64-apple-darwin17.7.0
  Host CPU: haswell

  Registered Targets:
    js     - JavaScript (asm.js, emscripten) backend
    x86    - 32-bit X86: Pentium-Pro and above
    x86-64 - 64-bit X86: EM64T and AMD64

I can make an issue out of this

2

Have you rebuilt tvm using the llvm-config from emsdk?