diff --git a/build/jam/BuildSetup b/build/jam/BuildSetup
index 3351d3bfbb..9a0d95f18e 100644
--- a/build/jam/BuildSetup
+++ b/build/jam/BuildSetup
@@ -465,16 +465,20 @@ HOST_UNARFLAGS		?= x ;
 
 # check the host platform compatibility
 SetPlatformCompatibilityFlagVariables HOST_PLATFORM : HOST : host
-	: linux freebsd darwin sunos ;
+	: linux freebsd darwin sunos cygwin ;
 
 if $(HOST_PLATFORM) = linux || $(HOST_PLATFORM) = freebsd
-	|| $(HOST_PLATFORM) = darwin {
+	|| $(HOST_PLATFORM) = darwin || $(HOST_PLATFORM) = cygwin {
 	# don't use lex: otherwise rc will not work correctly
 	if $(LEX) = lex {
 		LEX = flex ;
 	}
 }
 
+if $(HOST_PLATFORM) = cygwin {
+	HOST_LINKFLAGS += -Xlinker --allow-multiple-definition -Xlinker --enable-auto-import ;
+}
+
 HOST_CPU	?= $(OSPLAT:L) ;
 
 HOST_ARCH				?= $(HOST_CPU) ;
@@ -506,8 +510,10 @@ HOST_ASFLAGS = ;
 HOST_CCFLAGS += -Wno-multichar ;
 HOST_C++FLAGS += -Wno-multichar ;
 
-HOST_PIC_CCFLAGS += -fPIC ;
-HOST_PIC_C++FLAGS += -fPIC ;
+if $(HOST_PLATFORM) != cygwin {
+	HOST_PIC_CCFLAGS += -fPIC ;
+	HOST_PIC_C++FLAGS += -fPIC ;
+}
 
 HOST_KERNEL_CCFLAGS += $(HOST_GCC_BASE_FLAGS) -finline -fno-builtin
 	-DBOCHS_DEBUG_HACK=$(BOCHS_DEBUG_HACK) -D_KERNEL_MODE ;
@@ -613,8 +619,13 @@ if $(HOST_PLATFORM_BEOS_COMPATIBLE) {
 	HOST_LIBROOT = libroot_build.so ;
 	HOST_STATIC_LIBROOT = libroot_build.a ;
 	HOST_LIBBE = libbe_build.so ;
-	HOST_ADD_BUILD_COMPATIBILITY_LIB_DIR
-		= "export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$(HOST_BUILD_COMPATIBILITY_LIB_DIR)" ;
+	if $(HOST_PLATFORM) = cygwin {
+		HOST_ADD_BUILD_COMPATIBILITY_LIB_DIR
+			= "export PATH=$PATH:$(HOST_BUILD_COMPATIBILITY_LIB_DIR)" ;
+	} else {
+		HOST_ADD_BUILD_COMPATIBILITY_LIB_DIR
+			= "export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$(HOST_BUILD_COMPATIBILITY_LIB_DIR)" ;
+	}
 
 	# the C++ support library
 	if $(HOST_GCC_VERSION[1]) < 3 {
@@ -829,6 +840,7 @@ switch $(TARGET_PLATFORM) {
 	case linux		: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_LINUX ;
 	case freebsd	: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_FREEBSD ;
 	case darwin		: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_DARWIN ;
+	case cygwin	: TARGET_DEFINES += HAIKU_TARGET_PLATFORM_CYGWIN ;
 	case libbe_test	: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_LIBBE_TEST ;
 }
 
@@ -841,6 +853,7 @@ switch $(HOST_PLATFORM) {
 	case linux		: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_LINUX ;
 	case freebsd	: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_FREEBSD ;
 	case darwin		: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_DARWIN ;
+	case cygwin	: HOST_DEFINES += HAIKU_HOST_PLATFORM_CYGWIN ;
 }
 
 
diff --git a/build/jam/MainBuildRules b/build/jam/MainBuildRules
index 49e67c93b5..459b05e21b 100644
--- a/build/jam/MainBuildRules
+++ b/build/jam/MainBuildRules
@@ -535,6 +535,14 @@ rule BuildPlatformObjects
 	Objects $(sources) ;
 }
 
+actions CygwinExtensionFix
+{
+	if test -f $(1).exe ; then
+		rm -f $(1)
+		mv $(1).exe $(1)
+	fi
+}
+
 rule BuildPlatformMain
 {
 	# Usage BuildPlatformMain <target> : <sources> : <libraries> ;
@@ -566,6 +574,15 @@ rule BuildPlatformMain
 
 	Main $(target) : $(sources) ;
 	LinkAgainst $(target) : $(libs) ;
+	if $(HOST_PLATFORM) = cygwin {
+		# Cygwin gcc adds the ".exe" extension. We cannot force
+		# jam to use SUFEXE as haiku target executables are not
+		# supposed to have this extension, thus finding
+		# dependencies will fail for these.
+		# The hack is to remove the extension after a successful
+		# build of the Target.
+		CygwinExtensionFix $(target) ;
+	}
 }
 
 rule BuildPlatformSharedLibrary
@@ -584,6 +601,9 @@ rule BuildPlatformSharedLibrary
 	if $(HOST_PLATFORM) = darwin {
 		LINKFLAGS on $(target) = [ on $(target) return $(LINKFLAGS) ]
 			-dynamic -dynamiclib -Xlinker -flat_namespace ;
+	} else if $(HOST_PLATFORM) = cygwin {
+		LINKFLAGS on $(target) = [ on $(target) return $(LINKFLAGS) ]
+			-shared -Xlinker --allow-multiple-definition ;
 	} else {
 		LINKFLAGS on $(target) = [ on $(target) return $(LINKFLAGS) ]
 			-shared -Xlinker -soname=\"$(target:G=)\" ;