diff --git a/CMakeLists.txt b/CMakeLists.txt
index 978a162f72596..db94d1c7e6efb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -449,6 +449,8 @@ else()
     set(SWIFT_HOST_VARIANT_SDK_default "FREEBSD")
   elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "CYGWIN")
     set(SWIFT_HOST_VARIANT_SDK_default "CYGWIN")
+  elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "Windows")
+    set(SWIFT_HOST_VARIANT_SDK_default "WINDOWS")
   elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin")
     set(SWIFT_HOST_VARIANT_SDK_default "OSX")
   else()
@@ -475,6 +477,12 @@ else()
     set(SWIFT_HOST_VARIANT_ARCH_default "armv6")
   elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "armv7l")
     set(SWIFT_HOST_VARIANT_ARCH_default "armv7")
+  elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "AMD64")
+    set(SWIFT_HOST_VARIANT_ARCH_default "x86_64")
+  elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "IA64")
+    set(SWIFT_HOST_VARIANT_ARCH_default "itanium")
+  elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "x86")
+    set(SWIFT_HOST_VARIANT_ARCH_default "i686")
   else()
     message(FATAL_ERROR "Unrecognized architecture on host system: ${CMAKE_SYSTEM_PROCESSOR}")
   endif()
@@ -584,9 +592,14 @@ elseif("${SWIFT_HOST_VARIANT_SDK}" STREQUAL "CYGWIN")
       "Deployment OS for Swift host tools (the compiler) [windows].")
 
   configure_sdk_unix(CYGWIN "Cygwin" "windows" "cygwin" "windows" "x86_64-unknown-windows-cygnus" "/")
-  set(SWIFT_PRIMARY_VARIANT_SDK_default  "${SWIFT_HOST_VARIANT_SDK}")
+  set(SWIFT_PRIMARY_VARIANT_SDK_default "${SWIFT_HOST_VARIANT_SDK}")
   set(SWIFT_PRIMARY_VARIANT_ARCH_default "x86_64")
 
+elseif("${SWIFT_HOST_VARIANT_SDK}" STREQUAL "WINDOWS")
+  configure_sdk_windows(WINDOWS "Windows" "msvc" "${SWIFT_HOST_VARIANT_ARCH}")
+  set(SWIFT_PRIMARY_VARIANT_SDK_default  "${SWIFT_HOST_VARIANT_SDK}")
+  set(SWIFT_PRIMARY_VARIANT_ARCH_default "${SWIFT_HOST_VARIANT_ARCH}")
+
 elseif("${SWIFT_HOST_VARIANT_SDK}" MATCHES "(OSX|IOS*|TVOS*|WATCHOS*)")
 
   set(SWIFT_HOST_VARIANT "macosx" CACHE STRING
@@ -730,7 +743,7 @@ endif()
 
 # Should we cross-compile the standard library for Windows?
 is_sdk_requested(WINDOWS swift_build_windows)
-if(swift_build_windows)
+if(swift_build_windows AND NOT "${CMAKE_SYSTEM_NAME}" STREQUAL "Windows")
   configure_sdk_windows(WINDOWS "Windows" "msvc" i686)
 endif()
 
diff --git a/cmake/modules/SwiftConfigureSDK.cmake b/cmake/modules/SwiftConfigureSDK.cmake
index fc74dde43d51e..a4b4ff1a75158 100644
--- a/cmake/modules/SwiftConfigureSDK.cmake
+++ b/cmake/modules/SwiftConfigureSDK.cmake
@@ -157,7 +157,7 @@ macro(configure_sdk_windows prefix sdk_name environment architectures)
   set(SWIFT_SDK_${prefix}_DEPLOYMENT_VERSION "NOTFOUND")
   set(SWIFT_SDK_${prefix}_LIB_SUBDIR "windows")
   set(SWIFT_SDK_${prefix}_VERSION_MIN_NAME "NOTFOUND")
-  set(SWIFT_SDK_${prefix}_TRIPLE_NAME "NOTFOUND")
+  set(SWIFT_SDK_${prefix}_TRIPLE_NAME "Win32")
   set(SWIFT_SDK_${prefix}_ARCHITECTURES "${architectures}")
   set(SWIFT_SDK_${prefix}_OBJECT_FORMAT "COFF")
 
diff --git a/cmake/modules/SwiftSetIfArchBitness.cmake b/cmake/modules/SwiftSetIfArchBitness.cmake
index 468237d061d0a..5212cf3ccb854 100644
--- a/cmake/modules/SwiftSetIfArchBitness.cmake
+++ b/cmake/modules/SwiftSetIfArchBitness.cmake
@@ -8,6 +8,7 @@ function(set_if_arch_bitness var_name)
 
   if("${SIA_ARCH}" STREQUAL "i386" OR
      "${SIA_ARCH}" STREQUAL "i686" OR
+     "${SIA_ARCH}" STREQUAL "x86" OR
      "${SIA_ARCH}" STREQUAL "armv6" OR
      "${SIA_ARCH}" STREQUAL "armv7" OR
      "${SIA_ARCH}" STREQUAL "armv7k" OR