diff --git a/xpcom/Makefile.in b/xpcom/Makefile.in
index 66fa77a66925..b0f27ca85b4d 100644
--- a/xpcom/Makefile.in
+++ b/xpcom/Makefile.in
@@ -13,48 +13,8 @@ include $(DEPTH)/config/autoconf.mk
 MODULE		= xpcom
 GRE_MODULE	= 1
 
-DIRS		= \
-		idl-parser \
-		typelib \
-		string \
-		glue \
-		base \
-		ds \
-		io \
-		components \
-		threads \
-		reflect \
-                system \
-		../chrome \
-		build \
-		$(NULL)
-
-ifeq ($(OS_ARCH),WINNT)
-ifdef MOZ_DEBUG
-DIRS		+= windbgdlg
-endif
-endif
-
-ifdef ENABLE_TESTS
-TOOL_DIRS += \
-	tests \
-	sample \
-	typelib/xpt/tests \
-	$(NULL)
-
-#  Can't build internal xptcall tests that use symbols which are not exported.
-#TOOL_DIRS += \
-#	reflect/xptinfo/tests \
-#	reflect/xptcall/tests \
-#	$(NULL)
-endif
-
 # xpcom-config.h is generated by configure
 SDK_HEADERS	= xpcom-config.h
 
-ifdef DEHYDRA_PATH
-DIRS += analysis
-endif
-
 include $(topsrcdir)/config/rules.mk
 
diff --git a/xpcom/analysis/moz.build b/xpcom/analysis/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/analysis/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/base/moz.build b/xpcom/base/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/base/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/build/moz.build b/xpcom/build/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/build/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/components/moz.build b/xpcom/components/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/components/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/ds/moz.build b/xpcom/ds/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/ds/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/glue/Makefile.in b/xpcom/glue/Makefile.in
index cbc6e188c4a3..35233c6ad712 100644
--- a/xpcom/glue/Makefile.in
+++ b/xpcom/glue/Makefile.in
@@ -13,14 +13,6 @@ include $(srcdir)/objs.mk
 
 EXTRA_DEPS += $(srcdir)/objs.mk
 
-DIRS            = standalone nomozalloc
-
-# On win we build two glue libs - glue linked to crt dlls here and in staticruntime we build
-# a statically linked glue lib.
-ifeq ($(OS_ARCH),WINNT)
-DIRS += staticruntime
-endif
-
 MODULE		= xpcom
 LIBRARY_NAME	= xpcomglue_s
 DIST_INSTALL	= 1
diff --git a/xpcom/glue/moz.build b/xpcom/glue/moz.build
new file mode 100644
index 000000000000..be4b1333d0f8
--- /dev/null
+++ b/xpcom/glue/moz.build
@@ -0,0 +1,11 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += ['standalone', 'nomozalloc']
+
+# On win we build two glue libs - glue linked to crt dlls here and in staticruntime we build
+# a statically linked glue lib.
+if CONFIG['OS_ARCH'] == 'WINNT':
+    DIRS += ['staticruntime']
diff --git a/xpcom/glue/nomozalloc/moz.build b/xpcom/glue/nomozalloc/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/glue/nomozalloc/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/glue/standalone/Makefile.in b/xpcom/glue/standalone/Makefile.in
index e3f8971bd00f..38ed72d2dffa 100644
--- a/xpcom/glue/standalone/Makefile.in
+++ b/xpcom/glue/standalone/Makefile.in
@@ -13,12 +13,6 @@ include $(srcdir)/../objs.mk
 
 EXTRA_DEPS += $(srcdir)/../objs.mk
 
-# On win we build two glue libs - glue linked to crt dlls here and in staticruntime we build
-# a statically linked glue lib.
-ifeq ($(OS_ARCH),WINNT)
-DIRS += staticruntime
-endif
-
 MODULE		= xpcom
 LIBRARY_NAME	= xpcomglue
 DIST_INSTALL	= 1
diff --git a/xpcom/glue/standalone/moz.build b/xpcom/glue/standalone/moz.build
new file mode 100644
index 000000000000..32f810ba4936
--- /dev/null
+++ b/xpcom/glue/standalone/moz.build
@@ -0,0 +1,9 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# On win we build two glue libs - glue linked to crt dlls here and in staticruntime we build
+# a statically linked glue lib.
+if CONFIG['OS_ARCH'] == 'WINNT':
+    DIRS += ['staticruntime']
diff --git a/xpcom/glue/standalone/staticruntime/moz.build b/xpcom/glue/standalone/staticruntime/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/glue/standalone/staticruntime/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/glue/staticruntime/moz.build b/xpcom/glue/staticruntime/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/glue/staticruntime/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/idl-parser/moz.build b/xpcom/idl-parser/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/idl-parser/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/io/moz.build b/xpcom/io/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/io/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/moz.build b/xpcom/moz.build
new file mode 100644
index 000000000000..c15d6eaea001
--- /dev/null
+++ b/xpcom/moz.build
@@ -0,0 +1,38 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += [
+    'idl-parser',
+    'typelib',
+    'string',
+    'glue',
+    'base',
+    'ds',
+    'io',
+    'components',
+    'threads',
+    'reflect',
+    'system',
+    '../chrome',
+    'build',
+]
+
+if CONFIG['OS_ARCH'] == 'WINNT' and CONFIG['MOZ_DEBUG']:
+    DIRS += ['windbgdlg']
+
+TEST_TOOL_DIRS += [
+    'tests',
+    'sample',
+    'typelib/xpt/tests',
+]
+
+#  Can't build internal xptcall tests that use symbols which are not exported.
+#TEST_TOOL_DIRS += [
+#    'reflect/xptinfo/tests',
+#    'reflect/xptcall/tests,
+#]
+
+if CONFIG['DEHYDRA_PATH']:
+    DIRS += ['analysis']
diff --git a/xpcom/reflect/Makefile.in b/xpcom/reflect/Makefile.in
index 34e0c1a4c5de..d3e4e7659a08 100644
--- a/xpcom/reflect/Makefile.in
+++ b/xpcom/reflect/Makefile.in
@@ -11,7 +11,6 @@ VPATH		= @srcdir@
 include $(DEPTH)/config/autoconf.mk
 
 MODULE		= xpcom
-DIRS		= xptinfo xptcall
 
 include $(topsrcdir)/config/rules.mk
 
diff --git a/xpcom/reflect/moz.build b/xpcom/reflect/moz.build
new file mode 100644
index 000000000000..bb7f0d59b224
--- /dev/null
+++ b/xpcom/reflect/moz.build
@@ -0,0 +1,6 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += ['xptinfo', 'xptcall']
diff --git a/xpcom/reflect/xptcall/Makefile.in b/xpcom/reflect/xptcall/Makefile.in
index 6aedda93f602..d3e4e7659a08 100644
--- a/xpcom/reflect/xptcall/Makefile.in
+++ b/xpcom/reflect/xptcall/Makefile.in
@@ -11,7 +11,6 @@ VPATH		= @srcdir@
 include $(DEPTH)/config/autoconf.mk
 
 MODULE		= xpcom
-DIRS		= public src
 
 include $(topsrcdir)/config/rules.mk
 
diff --git a/xpcom/reflect/xptcall/moz.build b/xpcom/reflect/xptcall/moz.build
new file mode 100644
index 000000000000..077f40f4f5aa
--- /dev/null
+++ b/xpcom/reflect/xptcall/moz.build
@@ -0,0 +1,6 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += ['public', 'src']
diff --git a/xpcom/reflect/xptcall/public/moz.build b/xpcom/reflect/xptcall/public/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/reflect/xptcall/public/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/reflect/xptcall/src/Makefile.in b/xpcom/reflect/xptcall/src/Makefile.in
index 6c8221377251..b5d27a5691d5 100644
--- a/xpcom/reflect/xptcall/src/Makefile.in
+++ b/xpcom/reflect/xptcall/src/Makefile.in
@@ -14,9 +14,6 @@ MODULE		= xpcom
 LIBRARY_NAME	= xptcall
 MOZILLA_INTERNAL_API = 1
 
-DIRS		= md
-
-
 CPPSRCS		= xptcall.cpp
 
 # we don't want the shared lib, but we want to force the creation of a static lib.
diff --git a/xpcom/reflect/xptcall/src/md/Makefile.in b/xpcom/reflect/xptcall/src/md/Makefile.in
index 6ac6601fb1a6..ac724e1bc29c 100644
--- a/xpcom/reflect/xptcall/src/md/Makefile.in
+++ b/xpcom/reflect/xptcall/src/md/Makefile.in
@@ -10,15 +10,5 @@ VPATH		= @srcdir@
 
 include $(DEPTH)/config/autoconf.mk
 
-ifeq ($(OS_ARCH),OS2)
-DIRS = os2
-else
-ifeq ($(OS_ARCH),WINNT)
-DIRS = win32
-else
-DIRS = unix
-endif
-endif
-
 include $(topsrcdir)/config/rules.mk
 
diff --git a/xpcom/reflect/xptcall/src/md/moz.build b/xpcom/reflect/xptcall/src/md/moz.build
new file mode 100644
index 000000000000..c624e1522365
--- /dev/null
+++ b/xpcom/reflect/xptcall/src/md/moz.build
@@ -0,0 +1,13 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+arch = CONFIG['OS_ARCH']
+
+if arch == 'OS2':
+    DIRS += ['os2']
+elif arch == 'WINNT':
+    DIRS += ['win32']
+else:
+    DIRS += ['unix']
diff --git a/xpcom/reflect/xptcall/src/md/os2/moz.build b/xpcom/reflect/xptcall/src/md/os2/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/reflect/xptcall/src/md/os2/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/reflect/xptcall/src/md/test/moz.build b/xpcom/reflect/xptcall/src/md/test/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/reflect/xptcall/src/md/test/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/reflect/xptcall/src/md/unix/moz.build b/xpcom/reflect/xptcall/src/md/unix/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/reflect/xptcall/src/md/unix/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/reflect/xptcall/src/md/win32/moz.build b/xpcom/reflect/xptcall/src/md/win32/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/reflect/xptcall/src/md/win32/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/reflect/xptcall/src/moz.build b/xpcom/reflect/xptcall/src/moz.build
new file mode 100644
index 000000000000..eebb40730f17
--- /dev/null
+++ b/xpcom/reflect/xptcall/src/moz.build
@@ -0,0 +1,7 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+DIRS += ['md']
diff --git a/xpcom/reflect/xptcall/tests/moz.build b/xpcom/reflect/xptcall/tests/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/reflect/xptcall/tests/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/reflect/xptinfo/Makefile.in b/xpcom/reflect/xptinfo/Makefile.in
index 6aedda93f602..d3e4e7659a08 100644
--- a/xpcom/reflect/xptinfo/Makefile.in
+++ b/xpcom/reflect/xptinfo/Makefile.in
@@ -11,7 +11,6 @@ VPATH		= @srcdir@
 include $(DEPTH)/config/autoconf.mk
 
 MODULE		= xpcom
-DIRS		= public src
 
 include $(topsrcdir)/config/rules.mk
 
diff --git a/xpcom/reflect/xptinfo/moz.build b/xpcom/reflect/xptinfo/moz.build
new file mode 100644
index 000000000000..077f40f4f5aa
--- /dev/null
+++ b/xpcom/reflect/xptinfo/moz.build
@@ -0,0 +1,6 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += ['public', 'src']
diff --git a/xpcom/reflect/xptinfo/public/moz.build b/xpcom/reflect/xptinfo/public/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/reflect/xptinfo/public/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/reflect/xptinfo/src/moz.build b/xpcom/reflect/xptinfo/src/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/reflect/xptinfo/src/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/reflect/xptinfo/tests/moz.build b/xpcom/reflect/xptinfo/tests/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/reflect/xptinfo/tests/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/sample/Makefile.in b/xpcom/sample/Makefile.in
index b3faa209db1f..43602fc4144a 100644
--- a/xpcom/sample/Makefile.in
+++ b/xpcom/sample/Makefile.in
@@ -10,9 +10,6 @@ VPATH		= @srcdir@
 
 include $(DEPTH)/config/autoconf.mk
 
-# This makefile builds the "program" subdirectory.
-DIRS = program
-
 # MODULE specifies where header files from this Makefile are installed,
 # i.e. dist/include/xpcomsample
 MODULE		= xpcomsample
diff --git a/xpcom/sample/moz.build b/xpcom/sample/moz.build
new file mode 100644
index 000000000000..ccd9f915cf34
--- /dev/null
+++ b/xpcom/sample/moz.build
@@ -0,0 +1,6 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += ['program']
diff --git a/xpcom/sample/program/moz.build b/xpcom/sample/program/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/sample/program/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/string/Makefile.in b/xpcom/string/Makefile.in
index aa6350db5104..64dbc8166c01 100644
--- a/xpcom/string/Makefile.in
+++ b/xpcom/string/Makefile.in
@@ -11,11 +11,5 @@ VPATH		= @srcdir@
 include $(DEPTH)/config/autoconf.mk
 
 MODULE		= string
-DIRS		= public src
-
-#ifdef ENABLE_TESTS
-#DIRS		+= \
-#	tests
-#endif
 
 include $(topsrcdir)/config/rules.mk
diff --git a/xpcom/string/moz.build b/xpcom/string/moz.build
new file mode 100644
index 000000000000..077f40f4f5aa
--- /dev/null
+++ b/xpcom/string/moz.build
@@ -0,0 +1,6 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += ['public', 'src']
diff --git a/xpcom/string/public/moz.build b/xpcom/string/public/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/string/public/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/string/src/moz.build b/xpcom/string/src/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/string/src/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/stub/moz.build b/xpcom/stub/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/stub/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/system/moz.build b/xpcom/system/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/system/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/tests/Makefile.in b/xpcom/tests/Makefile.in
index 58a035fac58e..251ccbb0f687 100644
--- a/xpcom/tests/Makefile.in
+++ b/xpcom/tests/Makefile.in
@@ -1,4 +1,3 @@
-#
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
@@ -14,21 +13,6 @@ include $(DEPTH)/config/autoconf.mk
 MODULE		= xpcom
 FAIL_ON_WARNINGS = 1
 
-DIRS		= \
-  external \
-  component \
-  bug656331_component \
-  component_no_aslr \
-  $(NULL)
-
-ifeq ($(OS_ARCH),WINNT)
-DIRS		+= windows
-endif
-
-ifdef DEHYDRA_PATH
-DIRS += static-checker
-endif
-
 VPATH += $(topsrcdir)/build
 
 CPPSRCS = \
diff --git a/xpcom/tests/bug656331_component/moz.build b/xpcom/tests/bug656331_component/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/tests/bug656331_component/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/tests/component/moz.build b/xpcom/tests/component/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/tests/component/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/tests/component_no_aslr/moz.build b/xpcom/tests/component_no_aslr/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/tests/component_no_aslr/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/tests/external/moz.build b/xpcom/tests/external/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/tests/external/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/tests/moz.build b/xpcom/tests/moz.build
new file mode 100644
index 000000000000..23d97ef056f3
--- /dev/null
+++ b/xpcom/tests/moz.build
@@ -0,0 +1,17 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += [
+    'external',
+    'component',
+    'bug656331_component',
+    'component_no_aslr',
+]
+
+if CONFIG['OS_ARCH'] == 'WINNT':
+    DIRS += ['windows']
+
+if CONFIG['DEHYDRA_PATH']:
+    DIRS += ['static-checker']
diff --git a/xpcom/tests/static-checker/moz.build b/xpcom/tests/static-checker/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/tests/static-checker/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/tests/windows/moz.build b/xpcom/tests/windows/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/tests/windows/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/threads/moz.build b/xpcom/threads/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/threads/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/typelib/Makefile.in b/xpcom/typelib/Makefile.in
index 524472aa289a..d3e4e7659a08 100644
--- a/xpcom/typelib/Makefile.in
+++ b/xpcom/typelib/Makefile.in
@@ -11,7 +11,6 @@ VPATH		= @srcdir@
 include $(DEPTH)/config/autoconf.mk
 
 MODULE		= xpcom
-DIRS		= xpt xpidl
 
 include $(topsrcdir)/config/rules.mk
 
diff --git a/xpcom/typelib/moz.build b/xpcom/typelib/moz.build
new file mode 100644
index 000000000000..ad965e505970
--- /dev/null
+++ b/xpcom/typelib/moz.build
@@ -0,0 +1,6 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += ['xpt', 'xpidl']
diff --git a/xpcom/typelib/xpidl/moz.build b/xpcom/typelib/xpidl/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/typelib/xpidl/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/typelib/xpt/Makefile.in b/xpcom/typelib/xpt/Makefile.in
index 91fdd086fbab..d3e4e7659a08 100644
--- a/xpcom/typelib/xpt/Makefile.in
+++ b/xpcom/typelib/xpt/Makefile.in
@@ -12,7 +12,5 @@ include $(DEPTH)/config/autoconf.mk
 
 MODULE		= xpcom
 
-DIRS		= public src tools
-
 include $(topsrcdir)/config/rules.mk
 
diff --git a/xpcom/typelib/xpt/moz.build b/xpcom/typelib/xpt/moz.build
new file mode 100644
index 000000000000..5325c7c525c2
--- /dev/null
+++ b/xpcom/typelib/xpt/moz.build
@@ -0,0 +1,6 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += ['public', 'src', 'tools']
diff --git a/xpcom/typelib/xpt/public/moz.build b/xpcom/typelib/xpt/public/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/typelib/xpt/public/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/typelib/xpt/src/moz.build b/xpcom/typelib/xpt/src/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/typelib/xpt/src/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/typelib/xpt/tests/moz.build b/xpcom/typelib/xpt/tests/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/typelib/xpt/tests/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/typelib/xpt/tools/moz.build b/xpcom/typelib/xpt/tools/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/typelib/xpt/tools/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
diff --git a/xpcom/windbgdlg/moz.build b/xpcom/windbgdlg/moz.build
new file mode 100644
index 000000000000..58ce5e273390
--- /dev/null
+++ b/xpcom/windbgdlg/moz.build
@@ -0,0 +1,5 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+