diff --git a/include/bx/config.h b/include/bx/config.h
index f4650d4..fbf6e43 100644
--- a/include/bx/config.h
+++ b/include/bx/config.h
@@ -30,6 +30,7 @@
 				|| BX_PLATFORM_QNX \
 				|| BX_PLATFORM_RPI \
 				|| BX_PLATFORM_WINDOWS \
+                || BX_PLATFORM_WINRT \
 				? 1 : 0)
 #endif // BX_CONFIG_CRT_FILE_READER_WRITER
 
@@ -38,7 +39,7 @@
 #endif // BX_CONFIG_SEMAPHORE_PTHREAD
 
 #ifndef BX_CONFIG_SUPPORTS_THREADING
-#	define BX_CONFIG_SUPPORTS_THREADING !(BX_PLATFORM_EMSCRIPTEN || BX_PLATFORM_WINRT)
+#	define BX_CONFIG_SUPPORTS_THREADING !(BX_PLATFORM_EMSCRIPTEN)
 #endif // BX_CONFIG_SUPPORTS_THREADING
 
 #endif // BX_CONFIG_H_HEADER_GUARD
diff --git a/include/bx/os.h b/include/bx/os.h
index 5db19a2..c7f6ad8 100644
--- a/include/bx/os.h
+++ b/include/bx/os.h
@@ -10,6 +10,7 @@
 
 #if BX_PLATFORM_WINDOWS || BX_PLATFORM_WINRT
 #	include <windows.h>
+#   include "debug.h"
 #elif BX_PLATFORM_ANDROID \
 	|| BX_PLATFORM_EMSCRIPTEN \
 	|| BX_PLATFORM_FREEBSD \
diff --git a/include/bx/platform.h b/include/bx/platform.h
index cf5f7e6..88e4575 100644
--- a/include/bx/platform.h
+++ b/include/bx/platform.h
@@ -107,6 +107,7 @@
 #	define BX_PLATFORM_XBOX360 1
 #elif defined(_WIN32) || defined(_WIN64)
 // http://msdn.microsoft.com/en-us/library/6sehtctf.aspx
+#   include <windows.h>
 #	if !defined(WINAPI_FAMILY) || (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP)
 #		undef  BX_PLATFORM_WINDOWS
 #		if !defined(WINVER) && !defined(_WIN32_WINNT)
diff --git a/include/bx/sem.h b/include/bx/sem.h
index dcfe654..7822257 100644
--- a/include/bx/sem.h
+++ b/include/bx/sem.h
@@ -202,7 +202,11 @@ namespace bx
 	public:
 		Semaphore()
 		{
+#if BX_PLATFORM_WINRT
+            m_handle = CreateSemaphoreEx(NULL, 0, LONG_MAX, NULL, 0, SEMAPHORE_ALL_ACCESS);
+#else
 			m_handle = CreateSemaphore(NULL, 0, LONG_MAX, NULL);
+#endif
 			BX_CHECK(NULL != m_handle, "Failed to create Semaphore!");
 		}
 
@@ -219,7 +223,11 @@ namespace bx
 		bool wait(int32_t _msecs = -1) const
 		{
 			DWORD milliseconds = (0 > _msecs) ? INFINITE : _msecs;
-			return WAIT_OBJECT_0 == WaitForSingleObject(m_handle, milliseconds);
+#if BX_PLATFORM_WINRT
+			return WAIT_OBJECT_0 == WaitForSingleObjectEx(m_handle, milliseconds, FALSE);
+#else
+            return WAIT_OBJECT_0 == WaitForSingleObject(m_handle, milliseconds);
+#endif
 		}
 
 	private:
diff --git a/include/bx/thread.h b/include/bx/thread.h
index 79afb46..42cadc9 100644
--- a/include/bx/thread.h
+++ b/include/bx/thread.h
@@ -8,7 +8,11 @@
 
 #if BX_PLATFORM_POSIX
 #	include <pthread.h>
-#endif // BX_PLATFORM_POSIX
+#elif BX_PLATFORM_WINRT
+using namespace Platform;
+using namespace Windows::Foundation;
+using namespace Windows::System::Threading;
+#endif
 
 #include "sem.h"
 
@@ -27,7 +31,7 @@ namespace bx
 
 	public:
 		Thread()
-#if BX_PLATFORM_WINDOWS|BX_PLATFORM_XBOX360
+#if BX_PLATFORM_WINDOWS|BX_PLATFORM_XBOX360|BX_PLATFORM_WINRT
 			: m_handle(INVALID_HANDLE_VALUE)
 #elif BX_PLATFORM_POSIX
 			: m_handle(0)
@@ -65,6 +69,15 @@ namespace bx
 				, 0
 				, NULL
 				);
+#elif BX_PLATFORM_WINRT
+            m_handle = CreateEventEx(nullptr, nullptr, CREATE_EVENT_MANUAL_RESET, EVENT_ALL_ACCESS);
+            auto workItemHandler = ref new WorkItemHandler([=](IAsyncAction^)
+            {
+                m_exitCode = threadFunc(this);
+                SetEvent(m_handle);
+            }, CallbackContext::Any);
+
+            ThreadPool::RunAsync(workItemHandler, WorkItemPriority::Normal, WorkItemOptions::TimeSliced);
 #elif BX_PLATFORM_POSIX
 			int result;
 			BX_UNUSED(result);
@@ -99,6 +112,10 @@ namespace bx
 			GetExitCodeThread(m_handle, (DWORD*)&m_exitCode);
 			CloseHandle(m_handle);
 			m_handle = INVALID_HANDLE_VALUE;
+#elif BX_PLATFORM_WINRT
+            WaitForSingleObjectEx(m_handle, INFINITE, FALSE);
+            CloseHandle(m_handle);
+            m_handle = INVALID_HANDLE_VALUE;
 #elif BX_PLATFORM_POSIX
 			union
 			{
@@ -129,7 +146,7 @@ namespace bx
 			return m_fn(m_userData);
 		}
 
-#if BX_PLATFORM_WINDOWS|BX_PLATFORM_XBOX360
+#if BX_PLATFORM_WINDOWS|BX_PLATFORM_XBOX360|BX_PLATFORM_WINRT
 		static DWORD WINAPI threadFunc(LPVOID _arg)
 		{
 			Thread* thread = (Thread*)_arg;
@@ -150,7 +167,7 @@ namespace bx
 		}
 #endif // BX_PLATFORM_
 
-#if BX_PLATFORM_WINDOWS|BX_PLATFORM_XBOX360
+#if BX_PLATFORM_WINDOWS|BX_PLATFORM_XBOX360|BX_PLATFORM_WINRT
 		HANDLE m_handle;
 #elif BX_PLATFORM_POSIX
 		pthread_t m_handle;
@@ -194,7 +211,7 @@ namespace bx
 		uint32_t m_id;
 	};
 
-#else
+#elif !(BX_PLATFORM_WINRT)
 
 	class TlsData
 	{
diff --git a/scripts/toolchain.lua b/scripts/toolchain.lua
index 045f412..ce6c0b6 100755
--- a/scripts/toolchain.lua
+++ b/scripts/toolchain.lua
@@ -41,6 +41,7 @@ function toolchain(_buildDir, _libDir)
 			{ "vs2012-clang",  "Clang 3.6"         },
 			{ "vs2013-clang",  "Clang 3.6"         },
 			{ "winphone8",     "Windows Phone 8.0" },
+			{ "winphone81",   "Windows Phone 8.1" }
 		},
 	}
 
@@ -272,6 +273,12 @@ function toolchain(_buildDir, _libDir)
 			premake.vstudio.toolset = "v110_wp80"
 			location (_buildDir .. "projects/" .. _ACTION .. "-winphone8")
 		end
+
+		if "winphone81" == _OPTIONS["vs"] then
+			premake.vstudio.toolset = "v120_wp81"
+			platforms { "ARM" }
+			location (_buildDir .. "projects/" .. _ACTION .. "-winphone81")
+		end
 	end
 
 	flags {
@@ -345,6 +352,10 @@ function toolchain(_buildDir, _libDir)
 			"$(DXSDK_DIR)/lib/x64",
 		}
 
+	configuration { "ARM", "vs*" }
+		targetdir (_buildDir .. "arm_" .. _ACTION .. "/bin")
+		objdir (_buildDir .. "arm_" .. _ACTION .. "/obj")
+
 	configuration { "vs*-clang" }
 		buildoptions {
 			"-Qunused-arguments",
@@ -358,6 +369,9 @@ function toolchain(_buildDir, _libDir)
 		targetdir (_buildDir .. "win64_" .. _ACTION .. "-clang/bin")
 		objdir (_buildDir .. "win64_" .. _ACTION .. "-clang/obj")
 
+	configuration { "winphone8*" }
+		removeflags { "StaticRuntime", "NoExceptions" }
+
 	configuration { "mingw-*" }
 		defines { "WIN32" }
 		includedirs { bxDir .. "include/compat/mingw" }
diff --git a/tools/bin/windows/genie.exe b/tools/bin/windows/genie.exe
index 893d9c8..c8e8690 100644
Binary files a/tools/bin/windows/genie.exe and b/tools/bin/windows/genie.exe differ