diff --git a/build_scripts/Windows-msys2/build/build.bat b/build_scripts/Windows-msys2/build/build.bat
index 6dc9d8503..c83583180 100644
--- a/build_scripts/Windows-msys2/build/build.bat
+++ b/build_scripts/Windows-msys2/build/build.bat
@@ -26,6 +26,9 @@ if "%ParamWebui%"=="1" %EnvMSYS2Cmd% "pacman --noconfirm --needed -S mingw-w64-%
 :: Plugins
 if "%ParamPlugins%"=="1" %EnvMSYS2Cmd% "pacman --noconfirm --needed -S mingw-w64-%RsMSYS2Architecture%-speex mingw-w64-%RsMSYS2Architecture%-speexdsp mingw-w64-%RsMSYS2Architecture%-curl mingw-w64-%RsMSYS2Architecture%-libxslt mingw-w64-%RsMSYS2Architecture%-opencv mingw-w64-%RsMSYS2Architecture%-ffmpeg"
 
+:: Clang
+if "%ParamClang%"=="1" %EnvMSYS2Cmd% "pacman --noconfirm --needed -S mingw-w64-%RsMSYS2Architecture%-clang"
+
 :: Initialize environment
 call "%~dp0env.bat" %*
 if errorlevel 2 exit /B 2
@@ -63,7 +66,11 @@ echo Qt %QtVersion% >> buildinfo.txt
 
 call "%ToolsPath%\msys2-path.bat" "%SourcePath%" MSYS2SourcePath
 call "%ToolsPath%\msys2-path.bat" "%EnvMSYS2Path%" MSYS2EnvMSYS2Path
-%EnvMSYS2Cmd% "qmake "%MSYS2SourcePath%/RetroShare.pro" -r -spec win32-g++ %RS_QMAKE_CONFIG%"
+if "%ParamClang%"=="1" (
+	%EnvMSYS2Cmd% "qmake "%MSYS2SourcePath%/RetroShare.pro" -r -spec win32-clang-g++ %RS_QMAKE_CONFIG%"
+) else (
+	%EnvMSYS2Cmd% "qmake "%MSYS2SourcePath%/RetroShare.pro" -r -spec win32-g++ %RS_QMAKE_CONFIG%"
+)
 if errorlevel 1 goto error
 
 echo.
diff --git a/build_scripts/Windows-msys2/build/env-base.bat b/build_scripts/Windows-msys2/build/env-base.bat
index 2543eee7b..6f910649c 100644
--- a/build_scripts/Windows-msys2/build/env-base.bat
+++ b/build_scripts/Windows-msys2/build/env-base.bat
@@ -7,6 +7,7 @@ set ParamAutologin=0
 set ParamPlugins=0
 set ParamTor=0
 set ParamWebui=0
+set ParamClang=0
 set CoreCount=%NUMBER_OF_PROCESSORS%
 set RS_QMAKE_CONFIG=
 
@@ -31,6 +32,8 @@ if "%~1" NEQ "" (
 			set ParamWebui=1
 		) else if "%%~a"=="singlethread" (
 			set CoreCount=1
+		) else if "%%~a"=="clang" (
+			set ParamClang=1
 		) else if "%%~a"=="CONFIG+" (
 			set RS_QMAKE_CONFIG=%RS_QMAKE_CONFIG% %1
 		) else (
@@ -61,6 +64,10 @@ if "%Param64%"=="1" (
 	set RsMSYS2Architecture=x86_64
 )
 
+if "%ParamClang%"=="1" (
+	set RsArchitecture=%RsArchitecture%-Clang
+)
+
 if "%RsBit%"=="" goto :usage
 
 if "%ParamRelease%"=="1" (
@@ -89,7 +96,7 @@ exit /B 0
 
 :usage
 echo.
-echo Usage: 32^|64 release^|debug [version autologin plugins webui singlethread]
+echo Usage: 32^|64 release^|debug [autologin plugins webui singlethread clang]
 echo.
 echo Mandatory parameter
 echo 32^|64              32-bit or 64-bit Version
@@ -100,6 +107,7 @@ echo autologin          Build with autologin
 echo plugins            Build plugins
 echo webui              Enable JsonAPI and pack webui files
 echo singlethread       Use only 1 thread for building
+echo clang              Use clang compiler instead of GCC
 echo.
 echo Parameter for pack
 echo tor                Pack tor version
diff --git a/libbitdht/src/util/bdnet.cc b/libbitdht/src/util/bdnet.cc
index 4c5f681a6..ba8c33553 100644
--- a/libbitdht/src/util/bdnet.cc
+++ b/libbitdht/src/util/bdnet.cc
@@ -285,12 +285,6 @@ int sleep(unsigned int sec)
 }
 #endif
 
-int usleep(unsigned int usec)
-{ 
-	Sleep(usec / 1000); 
-	return 0;
-}
-
 /********************************** WINDOWS/UNIX SPECIFIC PART ******************/
 #else // UNIX
 
diff --git a/libbitdht/src/util/bdnet.h b/libbitdht/src/util/bdnet.h
index 639a2ed1a..89ecfa710 100644
--- a/libbitdht/src/util/bdnet.h
+++ b/libbitdht/src/util/bdnet.h
@@ -159,7 +159,6 @@ int     bdnet_w2u_errno(int error);
 #ifndef __MINGW64_VERSION_MAJOR
 int sleep(unsigned int sec);
 #endif
-int usleep(unsigned int usec);
 
 #endif // END of WINDOWS defines.
 /********************************** WINDOWS/UNIX SPECIFIC PART ******************/
diff --git a/libretroshare/src/libretroshare.pro b/libretroshare/src/libretroshare.pro
index 3f9dde680..29d317dbf 100644
--- a/libretroshare/src/libretroshare.pro
+++ b/libretroshare/src/libretroshare.pro
@@ -237,7 +237,7 @@ win32-x-g++ {
 }
 ################################# Windows ##########################################
 
-win32-g++ {
+win32-g++|win32-clang-g++ {
 	QMAKE_CC = $${QMAKE_CXX}
 	OBJECTS_DIR = temp/obj
 	MOC_DIR = temp/moc
@@ -843,7 +843,7 @@ rs_jsonapi {
     no_rs_cross_compiling {
         DUMMYRESTBEDINPUT = FORCE
         CMAKE_GENERATOR_OVERRIDE=""
-        win32-g++:CMAKE_GENERATOR_OVERRIDE="-G \"MSYS Makefiles\""
+        win32-g++|win32-clang-g++:CMAKE_GENERATOR_OVERRIDE="-G \"MSYS Makefiles\""
         genrestbedlib.name = Generating librestbed.
         genrestbedlib.input = DUMMYRESTBEDINPUT
         genrestbedlib.output = $$clean_path($${RESTBED_BUILD_PATH}/librestbed.a)
@@ -860,6 +860,7 @@ rs_jsonapi {
             mkdir -p $${RESTBED_BUILD_PATH} && cd $${RESTBED_BUILD_PATH} && \
             cmake \
                 -DCMAKE_CXX_COMPILER=$$QMAKE_CXX \
+                \"-DCMAKE_CXX_FLAGS=$${QMAKE_CXXFLAGS}\" \
                 $${CMAKE_GENERATOR_OVERRIDE} -DBUILD_SSL=OFF \
                 -DCMAKE_INSTALL_PREFIX=. -B. \
                 -H$$shell_path($${RESTBED_SRC_PATH}) && \
@@ -940,7 +941,7 @@ rs_broadcast_discovery {
     no_rs_cross_compiling {
         DUMMYQMAKECOMPILERINPUT = FORCE
         CMAKE_GENERATOR_OVERRIDE=""
-        win32-g++:CMAKE_GENERATOR_OVERRIDE="-G \"MSYS Makefiles\""
+        win32-g++|win32-clang-g++:CMAKE_GENERATOR_OVERRIDE="-G \"MSYS Makefiles\""
         udpdiscoverycpplib.name = Generating libudp-discovery.a.
         udpdiscoverycpplib.input = DUMMYQMAKECOMPILERINPUT
         udpdiscoverycpplib.output = $$clean_path($${UDP_DISCOVERY_BUILD_PATH}/libudp-discovery.a)
@@ -954,6 +955,7 @@ rs_broadcast_discovery {
             cd $${UDP_DISCOVERY_BUILD_PATH} && \
             cmake -DCMAKE_C_COMPILER=$$fixQmakeCC($$QMAKE_CC) \
                 -DCMAKE_CXX_COMPILER=$$QMAKE_CXX \
+                \"-DCMAKE_CXX_FLAGS=$${QMAKE_CXXFLAGS}\" \
                 $${CMAKE_GENERATOR_OVERRIDE} \
                 -DBUILD_EXAMPLE=OFF -DBUILD_TOOL=OFF \
                 -DCMAKE_INSTALL_PREFIX=. -B. \
diff --git a/libretroshare/src/use_libretroshare.pri b/libretroshare/src/use_libretroshare.pri
index 681805a7f..b8343ed36 100644
--- a/libretroshare/src/use_libretroshare.pri
+++ b/libretroshare/src/use_libretroshare.pri
@@ -46,7 +46,7 @@ rs_jsonapi {
         LIBS *= -L$$clean_path($${RESTBED_BUILD_PATH}/) -lrestbed
     } else:sLibs *= restbed
 
-    win32-g++:dLibs *= wsock32
+    win32-g++|win32-clang-g++:dLibs *= wsock32
 }
 
 linux-* {
@@ -55,7 +55,7 @@ linux-* {
 
 rs_deep_channels_index | rs_deep_files_index {
     mLibs += xapian
-    win32-g++:mLibs += rpcrt4
+    win32-g++|win32-clang-g++:mLibs += rpcrt4
 }
 
 rs_deep_files_index_ogg {
@@ -81,7 +81,7 @@ rs_broadcast_discovery {
         LIBS *= -L$$clean_path($${UDP_DISCOVERY_BUILD_PATH}) -ludp-discovery
     } else:sLibs *= udp-discovery
 
-    win32-g++:dLibs *= wsock32
+    win32-g++|win32-clang-g++:dLibs *= wsock32
 }
 
 static {
diff --git a/openpgpsdk/src/openpgpsdk.pro b/openpgpsdk/src/openpgpsdk.pro
index fa117381a..66341d0a3 100644
--- a/openpgpsdk/src/openpgpsdk.pro
+++ b/openpgpsdk/src/openpgpsdk.pro
@@ -21,7 +21,7 @@ linux-* {
 	OBJECTS_DIR = temp/linux/obj
 }
 
-win32-g++ {
+win32-g++|win32-clang-g++ {
 
     HEADERS += openpgpsdk/opsstring.h
     SOURCES += openpgpsdk/opsstring.c
diff --git a/retroshare-gui/src/retroshare-gui.pro b/retroshare-gui/src/retroshare-gui.pro
index a5d6838ae..9ff9f7ba2 100644
--- a/retroshare-gui/src/retroshare-gui.pro
+++ b/retroshare-gui/src/retroshare-gui.pro
@@ -59,7 +59,7 @@ rs_gui_cmark {
 
 		DUMMYCMARKINPUT = FORCE
 		CMAKE_GENERATOR_OVERRIDE=""
-		win32-g++:CMAKE_GENERATOR_OVERRIDE="-G \"MSYS Makefiles\""
+		win32-g++|win32-clang-g++:CMAKE_GENERATOR_OVERRIDE="-G \"MSYS Makefiles\""
 		gencmarklib.name = Generating libcmark.
 		gencmarklib.input = DUMMYCMARKINPUT
 		gencmarklib.output = $$clean_path($${CMARK_BUILD_PATH}/src/libcmark.a)
@@ -73,6 +73,7 @@ rs_gui_cmark {
 		    mkdir -p $${CMARK_BUILD_PATH} && cd $${CMARK_BUILD_PATH} && \
 		    cmake \
 		        -DCMAKE_CXX_COMPILER=$$QMAKE_CXX \
+                        \"-DCMAKE_CXX_FLAGS=$${QMAKE_CXXFLAGS}\" \
 		        $${CMAKE_GENERATOR_OVERRIDE} \
 		        -DCMAKE_INSTALL_PREFIX=. \
 		        -B. \
@@ -209,7 +210,7 @@ win32-x-g++ {
 
 #################################### Windows #####################################
 
-win32-g++ {
+win32-g++|win32-clang-g++ {
 	CONFIG(debug, debug|release) {
 		# show console output
 		CONFIG += console
diff --git a/retroshare-service/src/retroshare-service.pro b/retroshare-service/src/retroshare-service.pro
index 75cb0b581..454d2d216 100644
--- a/retroshare-service/src/retroshare-service.pro
+++ b/retroshare-service/src/retroshare-service.pro
@@ -81,7 +81,7 @@ macx {
 	INCLUDEPATH += . $$INC_DIR
 }
 
-win32-g++ {
+win32-g++|win32-clang-g++ {
 	CONFIG(debug, debug|release) {
 		# show console output
 		CONFIG += console
diff --git a/retroshare.pri b/retroshare.pri
index 6bccc1f5a..802a3cd75 100644
--- a/retroshare.pri
+++ b/retroshare.pri
@@ -631,7 +631,7 @@ android-* {
     RS_THREAD_LIB =
 }
 
-win32-g++ {
+win32-g++|win32-clang-g++ {
     !isEmpty(EXTERNAL_LIB_DIR) {
         message(Use pre-compiled libraries in $${EXTERNAL_LIB_DIR}.)
         PREFIX = $$system_path($$EXTERNAL_LIB_DIR)
@@ -683,6 +683,10 @@ win32-g++ {
     message(***retroshare.pri:Win32 PREFIX $$PREFIX INCLUDEPATH $$INCLUDEPATH QMAKE_LIBDIR $$QMAKE_LIBDIR DEFINES $$DEFINES)
 }
 
+win32-clang-g++ {
+    QMAKE_CXXFLAGS += -femulated-tls
+}
+
 macx-* {
 	rs_macos10.8 {
 		message(***retroshare.pri: Set Target and SDK to MacOS 10.8 )