diff --git a/Formula/llvm@6.rb b/Formula/llvm@6.rb
new file mode 100644
index 0000000000..b7cdd00062
--- /dev/null
+++ b/Formula/llvm@6.rb
@@ -0,0 +1,302 @@
+class CodesignRequirement < Requirement
+  fatal true
+
+  satisfy(:build_env => false) do
+    mktemp do
+      FileUtils.cp "/usr/bin/false", "llvm_check"
+      quiet_system "/usr/bin/codesign", "-f", "-s", "lldb_codesign", "--dryrun", "llvm_check"
+    end
+  end
+
+  def message
+    <<~EOS
+      lldb_codesign identity must be available to build with LLDB.
+      See: https://llvm.org/svn/llvm-project/lldb/trunk/docs/code-signing.txt
+    EOS
+  end
+end
+
+class LlvmAT6 < Formula
+  desc "Next-gen compiler infrastructure"
+  homepage "https://llvm.org/"
+
+  url "https://releases.llvm.org/6.0.1/llvm-6.0.1.src.tar.xz"
+  sha256 "b6d6c324f9c71494c0ccaf3dac1f16236d970002b42bb24a6c9e1634f7d0f4e2"
+
+  resource "clang" do
+    url "https://releases.llvm.org/6.0.1/cfe-6.0.1.src.tar.xz"
+    sha256 "7c243f1485bddfdfedada3cd402ff4792ea82362ff91fbdac2dae67c6026b667"
+  end
+
+  resource "clang-extra-tools" do
+    url "https://releases.llvm.org/6.0.1/clang-tools-extra-6.0.1.src.tar.xz"
+    sha256 "0d2e3727786437574835b75135f9e36f861932a958d8547ced7e13ebdda115f1"
+  end
+
+  resource "compiler-rt" do
+    url "https://releases.llvm.org/6.0.1/compiler-rt-6.0.1.src.tar.xz"
+    sha256 "f4cd1e15e7d5cb708f9931d4844524e4904867240c306b06a4287b22ac1c99b9"
+  end
+
+  resource "libcxx" do
+    url "https://releases.llvm.org/6.0.1/libcxx-6.0.1.src.tar.xz"
+    sha256 "7654fbc810a03860e6f01a54c2297a0b9efb04c0b9aa0409251d9bdb3726fc67"
+  end
+
+  resource "libunwind" do
+    url "https://releases.llvm.org/6.0.1/libunwind-6.0.1.src.tar.xz"
+    sha256 "a8186c76a16298a0b7b051004d0162032b9b111b857fbd939d71b0930fd91b96"
+  end
+
+  resource "lld" do
+    url "https://releases.llvm.org/6.0.1/lld-6.0.1.src.tar.xz"
+    sha256 "e706745806921cea5c45700e13ebe16d834b5e3c0b7ad83bf6da1f28b0634e11"
+  end
+
+  resource "lldb" do
+    url "https://releases.llvm.org/6.0.1/lldb-6.0.1.src.tar.xz"
+    sha256 "6b8573841f2f7b60ffab9715c55dceff4f2a44e5a6d590ac189d20e8e7472714"
+  end
+
+  resource "openmp" do
+    url "https://releases.llvm.org/6.0.1/openmp-6.0.1.src.tar.xz"
+    sha256 "66afca2b308351b180136cf899a3b22865af1a775efaf74dc8a10c96d4721c5a"
+  end
+
+  resource "polly" do
+    url "https://releases.llvm.org/6.0.1/polly-6.0.1.src.tar.xz"
+    sha256 "e7765fdf6c8c102b9996dbb46e8b3abc41396032ae2315550610cf5a1ecf4ecc"
+  end
+
+  keg_only :versioned_formula
+
+  option "with-toolchain", "Build with Toolchain to facilitate overriding system compiler"
+  option "with-lldb", "Build LLDB debugger"
+  option "with-python@2", "Build bindings against Homebrew's Python 2"
+
+  deprecated_option "with-python" => "with-python@2"
+
+  # https://llvm.org/docs/GettingStarted.html#requirement
+  depends_on "cmake" => :build
+  depends_on "libffi"
+
+  if MacOS.version <= :snow_leopard
+    depends_on "python@2"
+  else
+    depends_on "python@2" => :optional
+  end
+
+  if build.with? "lldb"
+    depends_on "swig" if MacOS.version >= :lion
+    depends_on CodesignRequirement
+  end
+
+  # According to the official llvm readme, GCC 4.7+ is required
+  fails_with :gcc_4_0
+  fails_with :gcc
+  ("4.3".."4.6").each do |n|
+    fails_with :gcc => n
+  end
+
+  # Clang cannot find system headers if Xcode CLT is not installed
+  pour_bottle? do
+    reason "The bottle needs the Xcode CLT to be installed."
+    satisfy { MacOS::CLT.installed? }
+  end
+
+  def install
+    # Apple's libstdc++ is too old to build LLVM
+    ENV.libcxx if ENV.compiler == :clang
+
+    if build.with? "python@2"
+      ENV.prepend_path "PATH", Formula["python@2"].opt_libexec/"bin"
+    end
+
+    (buildpath/"tools/clang").install resource("clang")
+    (buildpath/"tools/clang/tools/extra").install resource("clang-extra-tools")
+    (buildpath/"projects/openmp").install resource("openmp")
+    (buildpath/"projects/libcxx").install resource("libcxx")
+    (buildpath/"projects/libunwind").install resource("libunwind")
+    (buildpath/"tools/lld").install resource("lld")
+    (buildpath/"tools/polly").install resource("polly")
+
+    if build.with? "lldb"
+      if build.with? "python@2"
+        pyhome = `python-config --prefix`.chomp
+        ENV["PYTHONHOME"] = pyhome
+        pylib = "#{pyhome}/lib/libpython2.7.dylib"
+        pyinclude = "#{pyhome}/include/python2.7"
+      end
+      (buildpath/"tools/lldb").install resource("lldb")
+
+      # Building lldb requires a code signing certificate.
+      # The instructions provided by llvm creates this certificate in the
+      # user's login keychain. Unfortunately, the login keychain is not in
+      # the search path in a superenv build. The following three lines add
+      # the login keychain to ~/Library/Preferences/com.apple.security.plist,
+      # which adds it to the superenv keychain search path.
+      mkdir_p "#{ENV["HOME"]}/Library/Preferences"
+      username = ENV["USER"]
+      system "security", "list-keychains", "-d", "user", "-s", "/Users/#{username}/Library/Keychains/login.keychain"
+    end
+
+    (buildpath/"projects/compiler-rt").install resource("compiler-rt")
+
+    # compiler-rt has some iOS simulator features that require i386 symbols
+    # I'm assuming the rest of clang needs support too for 32-bit compilation
+    # to work correctly, but if not, perhaps universal binaries could be
+    # limited to compiler-rt. llvm makes this somewhat easier because compiler-rt
+    # can almost be treated as an entirely different build from llvm.
+    ENV.permit_arch_flags
+
+    args = %W[
+      -DLIBOMP_ARCH=x86_64
+      -DLINK_POLLY_INTO_TOOLS=ON
+      -DLLVM_BUILD_EXTERNAL_COMPILER_RT=ON
+      -DLLVM_BUILD_LLVM_DYLIB=ON
+      -DLLVM_ENABLE_EH=ON
+      -DLLVM_ENABLE_FFI=ON
+      -DLLVM_ENABLE_LIBCXX=ON
+      -DLLVM_ENABLE_RTTI=ON
+      -DLLVM_INCLUDE_DOCS=OFF
+      -DLLVM_INSTALL_UTILS=ON
+      -DLLVM_OPTIMIZED_TABLEGEN=ON
+      -DLLVM_TARGETS_TO_BUILD=all
+      -DWITH_POLLY=ON
+      -DFFI_INCLUDE_DIR=#{Formula["libffi"].opt_lib}/libffi-#{Formula["libffi"].version}/include
+      -DFFI_LIBRARY_DIR=#{Formula["libffi"].opt_lib}
+    ]
+    args << "-DLLVM_CREATE_XCODE_TOOLCHAIN=ON" if build.with? "toolchain"
+
+    if build.with?("lldb") && build.with?("python@2")
+      args << "-DLLDB_RELOCATABLE_PYTHON=ON"
+      args << "-DPYTHON_LIBRARY=#{pylib}"
+      args << "-DPYTHON_INCLUDE_DIR=#{pyinclude}"
+    end
+
+    mkdir "build" do
+      system "cmake", "-G", "Unix Makefiles", "..", *(std_cmake_args + args)
+      system "make"
+      system "make", "install"
+      system "make", "install-xcode-toolchain" if build.with? "toolchain"
+    end
+
+    (share/"clang/tools").install Dir["tools/clang/tools/scan-{build,view}"]
+    (share/"cmake").install "cmake/modules"
+    inreplace "#{share}/clang/tools/scan-build/bin/scan-build", "$RealBin/bin/clang", "#{bin}/clang"
+    bin.install_symlink share/"clang/tools/scan-build/bin/scan-build", share/"clang/tools/scan-view/bin/scan-view"
+    man1.install_symlink share/"clang/tools/scan-build/man/scan-build.1"
+
+    # install llvm python bindings
+    (lib/"python2.7/site-packages").install buildpath/"bindings/python/llvm"
+    (lib/"python2.7/site-packages").install buildpath/"tools/clang/bindings/python/clang"
+  end
+
+  def caveats; <<~EOS
+    To use the bundled libc++ please add the following LDFLAGS:
+      LDFLAGS="-L#{opt_lib} -Wl,-rpath,#{opt_lib}"
+  EOS
+  end
+
+  test do
+    assert_equal prefix.to_s, shell_output("#{bin}/llvm-config --prefix").chomp
+
+    (testpath/"omptest.c").write <<~EOS
+      #include <stdlib.h>
+      #include <stdio.h>
+      #include <omp.h>
+
+      int main() {
+          #pragma omp parallel num_threads(4)
+          {
+            printf("Hello from thread %d, nthreads %d\\n", omp_get_thread_num(), omp_get_num_threads());
+          }
+          return EXIT_SUCCESS;
+      }
+    EOS
+
+    clean_version = version.to_s[/(\d+\.?)+/]
+
+    system "#{bin}/clang", "-L#{lib}", "-fopenmp", "-nobuiltininc",
+                           "-I#{lib}/clang/#{clean_version}/include",
+                           "omptest.c", "-o", "omptest"
+    testresult = shell_output("./omptest")
+
+    sorted_testresult = testresult.split("\n").sort.join("\n")
+    expected_result = <<~EOS
+      Hello from thread 0, nthreads 4
+      Hello from thread 1, nthreads 4
+      Hello from thread 2, nthreads 4
+      Hello from thread 3, nthreads 4
+    EOS
+    assert_equal expected_result.strip, sorted_testresult.strip
+
+    (testpath/"test.c").write <<~EOS
+      #include <stdio.h>
+
+      int main()
+      {
+        printf("Hello World!\\n");
+        return 0;
+      }
+    EOS
+
+    (testpath/"test.cpp").write <<~EOS
+      #include <iostream>
+
+      int main()
+      {
+        std::cout << "Hello World!" << std::endl;
+        return 0;
+      }
+    EOS
+
+    # Testing Command Line Tools
+    if MacOS::CLT.installed?
+      libclangclt = Dir["/Library/Developer/CommandLineTools/usr/lib/clang/#{MacOS::CLT.version.to_i}*"].last { |f| File.directory? f }
+
+      system "#{bin}/clang++", "-v", "-nostdinc",
+              "-I/Library/Developer/CommandLineTools/usr/include/c++/v1",
+              "-I#{libclangclt}/include",
+              "-I/usr/include", # need it because /Library/.../usr/include/c++/v1/iosfwd refers to <wchar.h>, which CLT installs to /usr/include
+              "test.cpp", "-o", "testCLT++"
+      assert_includes MachO::Tools.dylibs("testCLT++"), "/usr/lib/libc++.1.dylib"
+      assert_equal "Hello World!", shell_output("./testCLT++").chomp
+
+      system "#{bin}/clang", "-v", "-nostdinc",
+              "-I/usr/include", # this is where CLT installs stdio.h
+              "test.c", "-o", "testCLT"
+      assert_equal "Hello World!", shell_output("./testCLT").chomp
+    end
+
+    # Testing Xcode
+    if MacOS::Xcode.installed?
+      libclangxc = Dir["#{MacOS::Xcode.toolchain_path}/usr/lib/clang/#{DevelopmentTools.clang_version}*"].last { |f| File.directory? f }
+
+      system "#{bin}/clang++", "-v", "-nostdinc",
+              "-I#{MacOS::Xcode.toolchain_path}/usr/include/c++/v1",
+              "-I#{libclangxc}/include",
+              "-I#{MacOS.sdk_path}/usr/include",
+              "test.cpp", "-o", "testXC++"
+      assert_includes MachO::Tools.dylibs("testXC++"), "/usr/lib/libc++.1.dylib"
+      assert_equal "Hello World!", shell_output("./testXC++").chomp
+
+      system "#{bin}/clang", "-v", "-nostdinc",
+              "-I#{MacOS.sdk_path}/usr/include",
+              "test.c", "-o", "testXC"
+      assert_equal "Hello World!", shell_output("./testXC").chomp
+    end
+
+    # link against installed libc++
+    # related to https://github.com/Homebrew/legacy-homebrew/issues/47149
+    system "#{bin}/clang++", "-v", "-nostdinc",
+            "-std=c++11", "-stdlib=libc++",
+            "-I#{MacOS::Xcode.toolchain_path}/usr/include/c++/v1",
+            "-I#{libclangxc}/include",
+            "-I#{MacOS.sdk_path}/usr/include",
+            "-L#{lib}",
+            "-Wl,-rpath,#{lib}", "test.cpp", "-o", "test"
+    assert_includes MachO::Tools.dylibs("test"), "#{opt_lib}/libc++.1.dylib"
+    assert_equal "Hello World!", shell_output("./test").chomp
+  end
+end