Comment 2 for bug 1365432

CMake Warning at CMakeLists.txt:253 (FIND_PACKAGE):
  By not providing "FindLLVM.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "LLVM", but
  CMake did not find one.

  Could not find a package configuration file provided by "LLVM" with any of
  the following names:

    LLVMConfig.cmake
    llvm-config.cmake

  Add the installation prefix of "LLVM" to CMAKE_PREFIX_PATH or set
  "LLVM_DIR" to a directory containing one of the above files. If "LLVM"
  provides a separate development package or SDK, be sure it has been
  installed.

Searching for system CLANG libraries
Did not find CLANG libraries
Compiler optimization may lead to broken Lapack build.
  If release build produces incorrect results (e.g. svd(rand(4)) is all NaN)
  you should to disable optimization when compiling dlamch.c and slamch.c

but both LLVM, llvm-dev and clang are installed.