diff --git a/libcxx/cmake/caches/MinGW.cmake b/libcxx/cmake/caches/MinGW.cmake
new file mode 100644
--- /dev/null
+++ b/libcxx/cmake/caches/MinGW.cmake
@@ -0,0 +1,20 @@
+set(LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY OFF CACHE BOOL "")
+set(LIBCXX_HAS_WIN32_THREAD_API ON CACHE BOOL "")
+
+set(LIBCXX_CXX_ABI libcxxabi CACHE STRING "")
+set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
+
+set(LIBCXXABI_ENABLE_SHARED OFF CACHE BOOL "")
+set(LIBCXX_ENABLE_STATIC_ABI_LIBRARY ON CACHE BOOL "")
+
+set(LIBCXX_USE_COMPILER_RT ON CACHE BOOL "")
+set(LIBCXXABI_USE_COMPILER_RT ON CACHE BOOL "")
+set(LIBUNWIND_USE_COMPILER_RT ON CACHE BOOL "")
+
+set(LIBCXX_TARGET_INFO "libcxx.test.target_info.MingwLocalTI" CACHE STRING "")
+
+# Without these flags, 'long double' (which is 80 bit on x86 mingw, but
+# 64 bit in MSVC) isn't handled correctly in printf.
+set(CMAKE_C_FLAGS "-D__USE_MINGW_ANSI_STDIO=1" CACHE STRING "")
+set(CMAKE_CXX_FLAGS "-D__USE_MINGW_ANSI_STDIO=1" CACHE STRING "")
+set(LIBCXX_TEST_COMPILER_FLAGS "-D__USE_MINGW_ANSI_STDIO=1" CACHE STRING "")
diff --git a/libcxx/docs/index.rst b/libcxx/docs/index.rst
--- a/libcxx/docs/index.rst
+++ b/libcxx/docs/index.rst
@@ -116,7 +116,7 @@
 macOS 10.9+     i386, x86_64, arm64       Building the shared library itself requires targetting macOS 10.11+
 FreeBSD 10+     i386, x86_64, arm
 Linux           i386, x86_64, arm, arm64
-Windows         x86_64
+Windows         x86_64                    Both MSVC and MinGW style environments
 =============== ========================= ============================
 
 Generally speaking, libc++ should work on any platform that provides a fairly complete
diff --git a/libcxx/utils/ci/buildkite-pipeline.yml b/libcxx/utils/ci/buildkite-pipeline.yml
--- a/libcxx/utils/ci/buildkite-pipeline.yml
+++ b/libcxx/utils/ci/buildkite-pipeline.yml
@@ -506,8 +506,8 @@
     timeout_in_minutes: 120
 
   # Tests on non-Unix platforms
-  - label: "Windows (DLL)"
-    command: "bash libcxx/utils/ci/run-buildbot windows-dll"
+  - label: "MSVC (DLL)"
+    command: "bash libcxx/utils/ci/run-buildbot msvc-dll"
     artifact_paths:
       - "**/test-results.xml"
     agents:
@@ -518,8 +518,32 @@
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Windows (Static)"
-    command: "bash libcxx/utils/ci/run-buildbot windows-static"
+  - label: "MSVC (Static)"
+    command: "bash libcxx/utils/ci/run-buildbot msvc-static"
+    artifact_paths:
+      - "**/test-results.xml"
+    agents:
+      queue: "windows"
+    retry:
+      automatic:
+        - exit_status: -1  # Agent was lost
+          limit: 2
+    timeout_in_minutes: 120
+
+  - label: "MinGW (DLL)"
+    command: "bash libcxx/utils/ci/run-buildbot mingw-dll"
+    artifact_paths:
+      - "**/test-results.xml"
+    agents:
+      queue: "windows"
+    retry:
+      automatic:
+        - exit_status: -1  # Agent was lost
+          limit: 2
+    timeout_in_minutes: 120
+
+  - label: "MinGW (Static)"
+    command: "bash libcxx/utils/ci/run-buildbot mingw-static"
     artifact_paths:
       - "**/test-results.xml"
     agents:
diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -601,7 +601,7 @@
                    -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in"
     check-runtimes
 ;;
-windows-dll)
+msvc-dll)
     clean
     # TODO: Currently, building with the experimental library breaks running
     # tests (the test linking look for the c++experimental library with the
@@ -613,12 +613,43 @@
     echo "+++ Running the libc++ tests"
     ${NINJA} -vC "${BUILD_DIR}" check-cxx
 ;;
-windows-static)
+msvc-static)
     clean
     generate-cmake-libcxx-win -DLIBCXX_ENABLE_SHARED=OFF
     echo "+++ Running the libc++ tests"
     ${NINJA} -vC "${BUILD_DIR}" check-cxx
 ;;
+mingw-dll)
+    clean
+    # Explicitly specify the compiler with a triple prefix. The CI
+    # environment has got two installations of Clang; the default one
+    # defaults to MSVC mode, while there's an installation of llvm-mingw
+    # further back in PATH. By calling the compiler with an explicit
+    # triple prefix, we use the one that is bundled with a mingw sysroot.
+    generate-cmake \
+          -DCMAKE_C_COMPILER=x86_64-w64-mingw32-clang \
+          -DCMAKE_CXX_COMPILER=x86_64-w64-mingw32-clang++ \
+          -C "${MONOREPO_ROOT}/libcxx/cmake/caches/MinGW.cmake"
+    echo "+++ Running the libc++ tests"
+    ${NINJA} -vC "${BUILD_DIR}" check-cxx
+;;
+mingw-static)
+    clean
+    generate-cmake \
+          -DCMAKE_C_COMPILER=x86_64-w64-mingw32-clang \
+          -DCMAKE_CXX_COMPILER=x86_64-w64-mingw32-clang++ \
+          -C "${MONOREPO_ROOT}/libcxx/cmake/caches/MinGW.cmake" \
+          -DLIBCXX_ENABLE_SHARED=OFF \
+          -DLIBUNWIND_ENABLE_SHARED=OFF
+    # When building a static lib, the cxx build target doesn't have a
+    # dependency on libunwind. Build libunwind specifically first, so we
+    # link against that instead of the toolchain's shared libunwind
+    # (which isn't found when tests are run with a limited PATH).
+    echo "+++ Building a static libunwind"
+    ${NINJA} -vC "${BUILD_DIR}" unwind
+    echo "+++ Running the libc++ tests"
+    ${NINJA} -vC "${BUILD_DIR}" check-cxx
+;;
 aix)
     export CC=ibm-clang
     export CXX=ibm-clang++_r