Index: uspace/Makefile.common
===================================================================
--- uspace/Makefile.common	(revision 0feaae499ef0f72ed8da9eb641f673fab5cbaf7d)
+++ uspace/Makefile.common	(revision e6910c8cba8ef767d08e484d4d27dc60eb1d67ef)
@@ -44,4 +44,6 @@
 #   EXTRA_CLEAN        additional cleanup targets
 #
+#   POSIX_COMPAT       set to 'y' to use POSIX compatibility layer
+#
 # Optionally, for a binary:
 #   STATIC_NEEDED      set to 'y' for init binaries, will build statically
@@ -104,4 +106,6 @@
 LIBSOFTINT_PREFIX = $(LIB_PREFIX)/softint
 
+LIBPOSIX_PREFIX = $(LIB_PREFIX)/posix
+
 LIBBLOCK_PREFIX = $(LIB_PREFIX)/block
 LIBFS_PREFIX = $(LIB_PREFIX)/fs
@@ -213,21 +217,26 @@
 JOBFILE = $(LIBC_PREFIX)/../../../tools/jobfile.py
 
+ifeq ($(POSIX_COMPAT),y)
+	CFLAGS = -I$(LIBPOSIX_PREFIX)
+	LIBS += $(LIBPOSIX_PREFIX)/libposix.a
+endif
+
 ifeq ($(COMPILER),gcc_cross)
-	CFLAGS = $(GCC_CFLAGS) $(EXTRA_CFLAGS)
+	CFLAGS += $(GCC_CFLAGS) $(EXTRA_CFLAGS)
 	DEPEND_DEFS = $(DEFS) $(CONFIG_DEFS)
 endif
 
 ifeq ($(COMPILER),gcc_native)
-	CFLAGS = $(GCC_CFLAGS) $(EXTRA_CFLAGS)
+	CFLAGS += $(GCC_CFLAGS) $(EXTRA_CFLAGS)
 	DEPEND_DEFS = $(DEFS) $(CONFIG_DEFS)
 endif
 
 ifeq ($(COMPILER),icc)
-	CFLAGS = $(ICC_CFLAGS) $(EXTRA_CFLAGS)
+	CFLAGS += $(ICC_CFLAGS) $(EXTRA_CFLAGS)
 	DEPEND_DEFS = $(DEFS) $(CONFIG_DEFS)
 endif
 
 ifeq ($(COMPILER),clang)
-	CFLAGS = $(CLANG_CFLAGS) $(EXTRA_CFLAGS)
+	CFLAGS += $(CLANG_CFLAGS) $(EXTRA_CFLAGS)
 	DEPEND_DEFS = $(DEFS) $(CONFIG_DEFS)
 endif