--- config/rules.mk.orig	Wed May  2 05:16:35 2012
+++ config/rules.mk	Fri May 11 08:42:50 2012
@@ -1479,7 +1487,7 @@ $(XPIDL_GEN_DIR)/%.h: %.idl $(XPIDL_DEPS) $(XPIDL_GEN_
 	$(PYTHON_PATH) \
 	  -I$(topsrcdir)/other-licenses/ply \
 	  -I$(topsrcdir)/xpcom/idl-parser \
-	  $(topsrcdir)/xpcom/idl-parser/header.py --cachedir=$(DEPTH)/xpcom/idl-parser $(XPIDL_FLAGS) $(_VPATH_SRCS) -d $(MDDEPDIR)/$(@F).pp -o $@
+	  $(topsrcdir)/xpcom/idl-parser/header.py --cachedir=$(DEPTH)/xpcom/idl-parser/cache $(XPIDL_FLAGS) $(_VPATH_SRCS) -d $(MDDEPDIR)/$(@F).pp -o $@
 	@if test -n "$(findstring $*.h, $(EXPORTS))"; \
 	  then echo "*** WARNING: file $*.h generated from $*.idl overrides $(srcdir)/$*.h"; else true; fi
 
@@ -1492,7 +1500,7 @@ $(XPIDL_GEN_DIR)/%.xpt: %.idl $(XPIDL_DEPS) $(XPIDL_GE
 	  -I$(topsrcdir)/other-licenses/ply \
 	  -I$(topsrcdir)/xpcom/idl-parser \
 	  -I$(topsrcdir)/xpcom/typelib/xpt/tools \
-	  $(topsrcdir)/xpcom/idl-parser/typelib.py --cachedir=$(DEPTH)/xpcom/idl-parser $(XPIDL_FLAGS) $(_VPATH_SRCS) -d $(MDDEPDIR)/$(@F).pp -o $@
+	  $(topsrcdir)/xpcom/idl-parser/typelib.py --cachedir=$(DEPTH)/xpcom/idl-parser/cache $(XPIDL_FLAGS) $(_VPATH_SRCS) -d $(MDDEPDIR)/$(@F).pp -o $@
 
 # no need to link together if XPIDLSRCS contains only XPIDL_MODULE
 ifneq ($(XPIDL_MODULE).idl,$(strip $(XPIDLSRCS)))
--- js/src/config/rules.mk.orig	Fri May 11 08:42:57 2012
+++ js/src/config/rules.mk	Fri May 11 08:43:15 2012
@@ -1479,7 +1479,7 @@ $(XPIDL_GEN_DIR)/%.h: %.idl $(XPIDL_DEPS) $(XPIDL_GEN_
 	$(PYTHON_PATH) \
 	  -I$(topsrcdir)/other-licenses/ply \
 	  -I$(topsrcdir)/xpcom/idl-parser \
-	  $(topsrcdir)/xpcom/idl-parser/header.py --cachedir=$(DEPTH)/xpcom/idl-parser $(XPIDL_FLAGS) $(_VPATH_SRCS) -d $(MDDEPDIR)/$(@F).pp -o $@
+	  $(topsrcdir)/xpcom/idl-parser/header.py --cachedir=$(DEPTH)/xpcom/idl-parser/cache $(XPIDL_FLAGS) $(_VPATH_SRCS) -d $(MDDEPDIR)/$(@F).pp -o $@
 	@if test -n "$(findstring $*.h, $(EXPORTS))"; \
 	  then echo "*** WARNING: file $*.h generated from $*.idl overrides $(srcdir)/$*.h"; else true; fi
 
@@ -1492,7 +1492,7 @@ $(XPIDL_GEN_DIR)/%.xpt: %.idl $(XPIDL_DEPS) $(XPIDL_GE
 	  -I$(topsrcdir)/other-licenses/ply \
 	  -I$(topsrcdir)/xpcom/idl-parser \
 	  -I$(topsrcdir)/xpcom/typelib/xpt/tools \
-	  $(topsrcdir)/xpcom/idl-parser/typelib.py --cachedir=$(DEPTH)/xpcom/idl-parser $(XPIDL_FLAGS) $(_VPATH_SRCS) -d $(MDDEPDIR)/$(@F).pp -o $@
+	  $(topsrcdir)/xpcom/idl-parser/typelib.py --cachedir=$(DEPTH)/xpcom/idl-parser/cache $(XPIDL_FLAGS) $(_VPATH_SRCS) -d $(MDDEPDIR)/$(@F).pp -o $@
 
 # no need to link together if XPIDLSRCS contains only XPIDL_MODULE
 ifneq ($(XPIDL_MODULE).idl,$(strip $(XPIDLSRCS)))
--- js/xpconnect/src/Makefile.in.orig	Fri May 11 08:43:27 2012
+++ js/xpconnect/src/Makefile.in	Fri May 11 08:44:03 2012
@@ -151,7 +151,7 @@ dom_quickstubs.cpp: $(srcdir)/dom_quickstubs.qsconf \
 	  -I$(topsrcdir)/xpcom/idl-parser \
 	  $(srcdir)/qsgen.py \
 	  --idlpath=$(DEPTH)/dist/idl \
-	  --cachedir=$(DEPTH)/xpcom/idl-parser \
+	  --cachedir=$(DEPTH)/xpcom/idl-parser/cache \
 	  --header-output dom_quickstubs.h \
 	  --stub-output dom_quickstubs.cpp \
 	  --makedepend-output $(MDDEPDIR)/dom_qsgen.pp \
@@ -172,7 +172,7 @@ dombindings_gen.h: $(srcdir)/dombindings.conf \
 	  -I$(topsrcdir)/xpcom/idl-parser \
 	  $(srcdir)/dombindingsgen.py \
 	  --idlpath=$(DEPTH)/dist/idl \
-	  --cachedir=$(DEPTH)/xpcom/idl-parser \
+	  --cachedir=$(DEPTH)/xpcom/idl-parser/cache \
 	  --header-output dombindings_gen.h \
 	  $(srcdir)/dombindings.conf
 
@@ -189,7 +189,7 @@ dombindings_gen.cpp: $(srcdir)/dombindings.conf \
 	  -I$(topsrcdir)/xpcom/idl-parser \
 	  $(srcdir)/dombindingsgen.py \
 	  --idlpath=$(DEPTH)/dist/idl \
-	  --cachedir=$(DEPTH)/xpcom/idl-parser \
+	  --cachedir=$(DEPTH)/xpcom/idl-parser/cache \
 	  --stub-output dombindings_gen.cpp \
 	  --makedepend-output $(MDDEPDIR)/dombindingsgen.pp \
 	  $(srcdir)/dombindings.conf
@@ -208,7 +208,7 @@ DictionaryHelpers.h: $(srcdir)/dictionary_helper_gen.c
 	  -I$(topsrcdir)/xpcom/idl-parser \
 	  $(srcdir)/dictionary_helper_gen.py \
 	  -I $(DEPTH)/dist/idl \
-	  --cachedir=$(DEPTH)/xpcom/idl-parser \
+	  --cachedir=$(DEPTH)/xpcom/idl-parser/cache \
 	  --header-output DictionaryHelpers.h \
 	  $(srcdir)/dictionary_helper_gen.conf
 
@@ -223,7 +223,7 @@ DictionaryHelpers.cpp: $(srcdir)/dictionary_helper_gen
 	  -I$(topsrcdir)/xpcom/idl-parser \
 	  $(srcdir)/dictionary_helper_gen.py \
 	  -I $(DEPTH)/dist/idl \
-	  --cachedir=$(DEPTH)/xpcom/idl-parser \
+	  --cachedir=$(DEPTH)/xpcom/idl-parser/cache \
 	  --header-output DictionaryHelpers.h \
 	  --stub-output DictionaryHelpers.cpp \
 	  --makedepend-output $(MDDEPDIR)/dictionary_helper_gen.pp \
--- xpcom/idl-parser/Makefile.in.orig	Fri May 11 08:44:10 2012
+++ xpcom/idl-parser/Makefile.in	Fri May 11 08:44:29 2012
@@ -61,7 +61,7 @@ export:: $(PARSER_SRCS) $(PLY_PROGS)
 	$(PYTHON_PATH) \
 	  -I$(topsrcdir)/other-licenses/ply \
 	  -I$(topsrcdir)/xpcom/idl-parser \
-	  $(topsrcdir)/xpcom/idl-parser/header.py --cachedir=. --regen
+	  $(topsrcdir)/xpcom/idl-parser/header.py --cachedir=$(DEPTH)/xpcom/idl-parser/cache --regen
 
 check::
 	$(PYTHON_PATH) \
--- xpcom/typelib/xpidl/Makefile.in.orig	Fri May 11 08:44:51 2012
+++ xpcom/typelib/xpidl/Makefile.in	Fri May 11 08:45:09 2012
@@ -48,8 +48,8 @@ SDK_BINARY = \
   $(topsrcdir)/xpcom/idl-parser/xpidl.py \
   $(topsrcdir)/xpcom/idl-parser/header.py \
   $(topsrcdir)/xpcom/idl-parser/typelib.py \
-  $(DEPTH)/xpcom/idl-parser/xpidllex.py \
-  $(DEPTH)/xpcom/idl-parser/xpidlyacc.py \
+  $(DEPTH)/xpcom/idl-parser/cache/xpidllex.py \
+  $(DEPTH)/xpcom/idl-parser/cache/xpidlyacc.py \
   $(NULL)
 
 ifndef MOZ_SYSTEM_PLY