Index: libcxx/docs/BuildingLibcxx.rst
===================================================================
--- libcxx/docs/BuildingLibcxx.rst
+++ libcxx/docs/BuildingLibcxx.rst
@@ -72,10 +72,11 @@
 Experimental Support for Windows
 --------------------------------
 
-The Windows support requires building with clang-cl as cl does not support one
-required extension: `#include_next`.  Furthermore, VS 2015 or newer (19.00) is
-required.  In the case of clang-cl, we need to specify the "MS Compatibility
-Version" as it defaults to 2014 (18.00).
+libcxx supports being built with clang-cl, but not with MSVC's cl.exe, as
+cl doesn't support the `#include_next` extension. Furthermore, VS 2015 or
+newer (19.00) is required.
+
+libcxx also supports being built with clang targeting MinGW environments.
 
 CMake + Visual Studio
 ~~~~~~~~~~~~~~~~~~~~~
@@ -93,32 +94,62 @@
           \path\to\libcxx
   > cmake --build .
 
-CMake + ninja
-~~~~~~~~~~~~~
+CMake + ninja (MSVC)
+~~~~~~~~~~~~~~~~~~~~
 
 Building with ninja is required for development to enable tests.
-Unfortunately, doing so requires additional configuration as we cannot
-just specify a toolset.
+
+It can be built with CMake + ninja directly in a Windows Command Prompt,
+however running the tests require being run in an environment with a bash
+shell available, which can be provided e.g. by the MSYS2 project.
+
+This can be set up e.g. by starting a Visual Studio Tools Command Prompt
+(for getting the environment variables pointing to the headers and
+import libraries), and making sure that clang-cl is available in the
+path. From there, launch an MSYS2 shell via e.g.
+`\msys64\msys2_shell.cmd -full-path -mingw64` (preserving the earlier
+environment, allowing the MSVC headers/libraries and clang-cl to be found).
 
 .. code-block:: batch
 
   > cmake -G Ninja                                                                    ^
-          -DCMAKE_MAKE_PROGRAM=/path/to/ninja                                         ^
-          -DCMAKE_SYSTEM_NAME=Windows                                                 ^
           -DCMAKE_C_COMPILER=clang-cl                                                 ^
-          -DCMAKE_C_FLAGS="-fms-compatibility-version=19.00 --target=i686--windows"   ^
-          -DCMAKE_CXX_COMPILER=clang-cl                                                ^
-          -DCMAKE_CXX_FLAGS="-fms-compatibility-version=19.00 --target=i686--windows" ^
-          -DLLVM_PATH=/path/to/llvm/tree                                              ^
-          -DLIBCXX_ENABLE_SHARED=YES                                                  ^
-          -DLIBCXX_ENABLE_STATIC=NO                                                   ^
+          -DCMAKE_CXX_COMPILER=clang-cl                                               ^
+          -DLLVM_PATH=/path/to/llvm-project/llvm                                      ^
           -DLIBCXX_ENABLE_EXPERIMENTAL_LIBRARY=NO                                     ^
           \path\to\libcxx
-  > /path/to/ninja cxx
-  > /path/to/ninja check-cxx
+  > ninja cxx
+  > ninja check-cxx
+
+(Note that if the MSYS2 provided mingw-w64-x86_64-clang package is
+installed and is the first one in the path, that one ends up picked up
+when running tests. As that one defaults to a non-MSVC target, add
+`-DLIBCXX_TARGET_TRIPLE=x86_64-windows-msvc` to the cmake configuration
+in this case.)
+
+CMake + ninja (MinGW)
+~~~~~~~~~~~~~~~~~~~~~
 
-Note that the paths specified with backward slashes must use the `\\` as the
-directory separator as clang-cl may otherwise parse the path as an argument.
+libcxx can also be built in MinGW environments, e.g. in MSYS2.
+This requires clang to be available (installed from the
+`mingw-w64-x86_64-clang` package), together with CMake and ninja.
+
+.. code-block:: batch
+
+  > cmake -G Ninja                                                                    ^
+
+          -DCMAKE_C_COMPILER=clang                                                    ^
+          -DCMAKE_CXX_COMPILER=clang++                                                ^
+          -DLLVM_PATH=/path/to/llvm-project/llvm                                      ^
+          -DLIBCXX_ENABLE_EXPERIMENTAL_LIBRARY=NO                                     ^
+          -DLIBCXX_HAS_WIN32_THREAD_API=ON                                            ^
+          -DLIBCXX_CXX_ABI=libstdc++                                                  ^
+          /path/to/libcxx
+  > ninja cxx
+  > ninja check-cxx
+
+(In this configurations, tests don't currently work quite as well
+out of the box.)
 
 .. _`libc++abi`: http://libcxxabi.llvm.org/
 
Index: libcxx/www/index.html
===================================================================
--- libcxx/www/index.html
+++ libcxx/www/index.html
@@ -129,6 +129,12 @@
     <li>Linux x86_64</li>
   </ul>
 
+  <p>
+    The library also does work for Windows (both MSVC style environments,
+    built with clang-cl, and MinGW environments), although that platform
+    support is less mature than the platforms above.
+  </p>
+
   <!--=====================================================================-->
   <h2 id="dir-structure">Current Status</h2>
   <!--=====================================================================-->