--- mozilla/ipc/chromium/Makefile.in~
+++ mozilla/ipc/chromium/Makefile.in
@@ -43,6 +43,14 @@ include $(DEPTH)/config/autoconf.mk
 
 OS_CXXFLAGS := $(filter-out -fshort-wchar,$(OS_CXXFLAGS))
 
+# workaround IPC hang with libevent2
+ifndef MOZ_DEBUG
+ifneq (,$(filter 4.2.%, $(CXX_VERSION)))
+MOZ_OPTIMIZE_FLAGS = -O1
+OS_CXXFLAGS += $(MOZ_OPTIMIZE_FLAGS)
+endif
+endif
+
 LIBRARY_NAME = chromium_s
 FORCE_STATIC_LIB = 1
 LIBXUL_LIBRARY = 1
@@ -55,9 +60,7 @@ vpath %.c \
   $(srcdir)/src/third_party/libevent \
   $(NULL)
 else # } else {
-# message_pump_libevent.cc includes third_party/libevent/event.h,
-# which we put in $(DIST), see export rule below
-LOCAL_INCLUDES += -I$(DIST)
+LOCAL_INCLUDES += $(filter %/compat, $(MOZ_LIBEVENT_CFLAGS))
 endif # }
 
 vpath %.cc \