$ brew install  mongodb/brew/libmongocrypt
...
==> cmake . -DBUILD_VERSION=1.13.1 -DFETCHCONTENT_FULLY_DISCONNECTED=OFF
Last 15 lines from /Users/kevin.albertson/Library/Logs/Homebrew/libmongocrypt/01.cmake:
-- Looking for strings.h - found
-- Looking for gmtime_r
-- Looking for gmtime_r - found
Detected byte order: little endian
Adding -fPIC to compilation of kms_message_static components
compiling with unexported symbols list to hide bson symbols
-- Performing Test COMPILER_HAS_HIDDEN_VISIBILITY
-- Performing Test COMPILER_HAS_HIDDEN_VISIBILITY - Success
-- Performing Test COMPILER_HAS_HIDDEN_INLINE_VISIBILITY
-- Performing Test COMPILER_HAS_HIDDEN_INLINE_VISIBILITY - Success
-- Performing Test COMPILER_HAS_DEPRECATED_ATTR
-- Performing Test COMPILER_HAS_DEPRECATED_ATTR - Success
Adding -fPIC to compilation of mongocrypt_static components
compiling utilities
-- Configuring incomplete, errors occurred!

-- Using bundled libbson
CMake Error at _deps/embedded_mcd-src/src/libbson/CMakeLists.txt:37 (cmake_policy):
  Policy CMP0042 may not be set to OLD behavior because this version of CMake
  no longer supports it.  The policy was introduced in CMake version 3.0.0,
  and use of NEW behavior is now required.

  Please either update your CMakeLists.txt files to conform to the new
  behavior or use an older version of CMake that still supports the old
  behavior.  Run cmake --help-policy CMP0042 for more information.