diff --git a/mail/Makefile.in b/mail/Makefile.in
index 40f4af1f11..895b1db672 100644
--- a/mail/Makefile.in
+++ b/mail/Makefile.in
@@ -2,8 +2,8 @@
 # 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/.
 
-include $(moztopsrcdir)/config/config.mk
-include $(moztopsrcdir)/config/rules.mk
+include $(topsrcdir)/config/config.mk
+include $(topsrcdir)/config/rules.mk
 
 ifdef MAKENSISU
 # For Windows build the uninstaller during the application build since the
diff --git a/mail/app/Makefile.in b/mail/app/Makefile.in
index 7cd372db3b..82bf9565b3 100644
--- a/mail/app/Makefile.in
+++ b/mail/app/Makefile.in
@@ -6,8 +6,8 @@ dist_dest   = $(DIST)/$(MOZ_MACBUNDLE_NAME)
 
 AB_CD = $(MOZ_UI_LOCALE)
 
-GRE_MILESTONE = $(shell $(PYTHON3) $(moztopsrcdir)/config/printconfigsetting.py $(DIST)/bin/platform.ini Build Milestone)
-MOZ_BUILDID = $(shell $(PYTHON3) $(moztopsrcdir)/config/printconfigsetting.py $(DIST)/bin/platform.ini Build BuildID)
+GRE_MILESTONE = $(shell $(PYTHON3) $(topsrcdir)/config/printconfigsetting.py $(DIST)/bin/platform.ini Build Milestone)
+MOZ_BUILDID = $(shell $(PYTHON3) $(topsrcdir)/config/printconfigsetting.py $(DIST)/bin/platform.ini Build BuildID)
 
 # Build a binary bootstrapping with XRE_main
 
@@ -19,7 +19,7 @@ MOZ_WINCONSOLE = 0
 endif
 endif
 
-include $(moztopsrcdir)/config/config.mk
+include $(topsrcdir)/config/config.mk
 
 # If we are trying to show an error dialog about the lack of SSE2 support,
 # make sure that code itself doesn't use SSE2.
@@ -30,7 +30,7 @@ endif
 
 objdir = $(topobjdir)/comm/mail/app
 
-include $(moztopsrcdir)/config/rules.mk
+include $(topsrcdir)/config/rules.mk
 
 ifneq ($(OS_ARCH),WINNT)
 ifdef COMPILE_ENVIRONMENT
diff --git a/mail/branding/thunderbird/locales/Makefile.in b/mail/branding/thunderbird/locales/Makefile.in
index 6a10ada695..c0fdaa9993 100644
--- a/mail/branding/thunderbird/locales/Makefile.in
+++ b/mail/branding/thunderbird/locales/Makefile.in
@@ -5,4 +5,4 @@
 LOCALE_TOPDIR=$(commtopsrcdir)
 LOCALE_RELATIVEDIR=mail/branding/thunderbird/locales
 
-include $(moztopsrcdir)/config/config.mk
+include $(topsrcdir)/config/config.mk
diff --git a/mail/build.mk b/mail/build.mk
index ea17e13cb6..ea9196e73e 100644
--- a/mail/build.mk
+++ b/mail/build.mk
@@ -2,36 +2,39 @@
 # 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/.
 
+# Note that this file is "included" from $topsrcdir/Makefile.in, therefore
+# paths are relative to $topobjdir not the location of this file.
+
 package:
-	@$(MAKE) -C $(commtopobjdir)/mail/installer
+	@$(MAKE) -C comm/mail/installer
 
 package-compare:
-	@$(MAKE) -C $(commtopobjdir)/mail/installer package-compare
+	@$(MAKE) -C comm/mail/installer package-compare
 
 stage-package:
-	@$(MAKE) -C $(commtopobjdir)/mail/installer stage-package
+	@$(MAKE) -C comm/mail/installer stage-package
 
 install::
-	@$(MAKE) -C $(commtopobjdir)/mail/installer install
+	@$(MAKE) -C comm/mail/installer install
 
 source-package::
-	@$(MAKE) -C $(commtopobjdir)/mail/installer source-package
+	@$(MAKE) -C comm/mail/installer source-package
 
 upload::
-	@$(MAKE) -C $(commtopobjdir)/mail/installer upload
+	@$(MAKE) -C comm/mail/installer upload
 
 source-upload::
-	@$(MAKE) -C $(commtopobjdir)/mail/installer source-upload
+	@$(MAKE) -C comm/mail/installer source-upload
 
 hg-bundle::
-	@$(MAKE) -C $(commtopobjdir)/mail/installer hg-bundle
+	@$(MAKE) -C comm/mail/installer hg-bundle
 
 wget-en-US:
-	$(MAKE) -C $(commtopobjdir)/mail/locales wget-en-US
+	$(MAKE) -C comm/mail/locales wget-en-US
 
 merge-% post-merge-% installers-% langpack-% chrome-%:
-	$(MAKE) -C $(commtopobjdir)/mail/locales $@
+	$(MAKE) -C comm/mail/locales $@
 
 ifdef ENABLE_TESTS
-include $(commtopsrcdir)/mail/testsuite-targets.mk
+include $(topsrcdir)/comm/mail/testsuite-targets.mk
 endif
diff --git a/mail/components/search/mdimporter/Makefile.in b/mail/components/search/mdimporter/Makefile.in
index 5c8411a2a4..fbc6d27034 100644
--- a/mail/components/search/mdimporter/Makefile.in
+++ b/mail/components/search/mdimporter/Makefile.in
@@ -22,5 +22,5 @@ CFLAGS += -mmacosx-version-min=$(MACOSX_DEPLOYMENT_TARGET)
 # We don't need mozglue
 WRAP_LDFLAGS :=
 
-include $(moztopsrcdir)/config/rules.mk
+include $(topsrcdir)/config/rules.mk
 
diff --git a/mail/installer/Makefile.in b/mail/installer/Makefile.in
index 86cfbd7364..e99bdc71db 100644
--- a/mail/installer/Makefile.in
+++ b/mail/installer/Makefile.in
@@ -5,7 +5,7 @@
 STANDALONE_MAKEFILE := 1
 # DIST_SUBDIR := mail  # Not sure why TB is not using this
 
-include $(moztopsrcdir)/config/rules.mk
+include $(topsrcdir)/config/rules.mk
 
 MOZ_PKG_REMOVALS = $(srcdir)/removed-files.in
 
@@ -21,12 +21,12 @@ ifdef MOZ_ARTIFACT_BUILDS
 MOZ_PKG_FATAL_WARNINGS =
 endif
 
-DEFINES += -DPKG_LOCALE_MANIFEST=$(commtopobjdir)/mail/installer/locale-manifest.in
+DEFINES += -DPKG_LOCALE_MANIFEST=$(topobjdir)/comm/mail/installer/locale-manifest.in
 MOZ_CHROME_LOCALE_ENTRIES=@RESPATH@/chrome/
 
 MOZ_PKG_DUPEFLAGS = \
 	-f $(srcdir)/allowed-dupes.mn \
-	-f $(moztopsrcdir)/browser/installer/allowed-dupes.mn \
+	-f $(topsrcdir)/browser/installer/allowed-dupes.mn \
 	$(NULL)
 
 MOZ_NONLOCALIZED_PKG_LIST = \
@@ -135,7 +135,7 @@ MOZ_PACKAGER_MINIFY=1
 NON_OMNIJAR_FILES = defaults/messenger/mailViews.dat
 
 UPLOAD_EXTRA_FILES = $(MOZ_BUILT_FROM_FILE)
-include $(moztopsrcdir)/toolkit/mozapps/installer/packager.mk
+include $(topsrcdir)/toolkit/mozapps/installer/packager.mk
 
 ifeq (Darwin,$(OS_TARGET))
 BINPATH = $(_BINPATH)
@@ -184,7 +184,7 @@ DEFINES += -DTB_LIBOTR_PREBUILT
 endif
 
 libs::
-	$(MAKE) -C $(commtopobjdir)/mail/locales langpack
+	$(MAKE) -C $(DEPTH)/comm/mail/locales langpack
 
 ifeq (WINNT,$(OS_ARCH))
 PKGCOMP_FIND_OPTS =
diff --git a/mail/installer/windows/Makefile.in b/mail/installer/windows/Makefile.in
index b6324f8251..2a1f518bbf 100644
--- a/mail/installer/windows/Makefile.in
+++ b/mail/installer/windows/Makefile.in
@@ -2,7 +2,7 @@
 # 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/.
 
-include $(moztopsrcdir)/toolkit/mozapps/installer/package-name.mk
+include $(topsrcdir)/toolkit/mozapps/installer/package-name.mk
 
 CONFIG_DIR = instgen
 SFX_MODULE = $(commtopsrcdir)/other-licenses/7zstub/thunderbird/7zSD.sfx
@@ -30,7 +30,7 @@ BRANDING_FILES = \
 LOCALE_TOPDIR=$(commtopsrcdir)
 LOCALE_RELATIVEDIR=mail/installer/windows
 
-include $(moztopsrcdir)/config/config.mk
+include $(topsrcdir)/config/config.mk
 
 ifdef IS_LANGUAGE_REPACK
 PPL_LOCALE_ARGS = \
@@ -49,11 +49,11 @@ $(CONFIG_DIR)/setup.exe::
 	$(INSTALL) $(addprefix $(topsrcdir)/$(MOZ_BRANDING_DIRECTORY)/,$(BRANDING_FILES)) $(CONFIG_DIR)
 	$(call py_action,preprocessor,-Fsubstitution $(DEFINES) $(ACDEFINES) \
 	  $(srcdir)/nsis/defines.nsi.in -o $(CONFIG_DIR)/defines.nsi)
-	$(PYTHON3) $(moztopsrcdir)/toolkit/mozapps/installer/windows/nsis/preprocess-locale.py \
-	  --preprocess-locale $(moztopsrcdir) \
+	$(PYTHON3) $(topsrcdir)/toolkit/mozapps/installer/windows/nsis/preprocess-locale.py \
+	  --preprocess-locale $(topsrcdir) \
 	  $(PPL_LOCALE_ARGS) $(AB_CD) $(CONFIG_DIR)
 
 GARBARGE_DIRS += instgen
 
-include $(moztopsrcdir)/config/rules.mk
-include $(moztopsrcdir)/toolkit/mozapps/installer/windows/nsis/makensis.mk
+include $(topsrcdir)/config/rules.mk
+include $(topsrcdir)/toolkit/mozapps/installer/windows/nsis/makensis.mk
diff --git a/mail/locales/Makefile.in b/mail/locales/Makefile.in
index 147e24dc5f..513fa8814b 100644
--- a/mail/locales/Makefile.in
+++ b/mail/locales/Makefile.in
@@ -5,7 +5,7 @@
 LOCALE_TOPDIR=$(commtopsrcdir)
 LOCALE_RELATIVEDIR=mail/locales
 
-include $(moztopsrcdir)/config/config.mk
+include $(topsrcdir)/config/config.mk
 
 SUBMAKEFILES += \
 	$(DEPTH)/$(MOZ_BRANDING_DIRECTORY)/Makefile \
@@ -40,12 +40,12 @@ NON_OMNIJAR_FILES = defaults/messenger/mailViews.dat
 # be included in langpack xpis.
 DIST_SUBDIRS = $(DIST_SUBDIR)
 
-include $(moztopsrcdir)/config/rules.mk
+include $(topsrcdir)/config/rules.mk
 
-include $(moztopsrcdir)/toolkit/locales/l10n.mk
+include $(topsrcdir)/toolkit/locales/l10n.mk
 
 ifeq ($(VCS_CHECKOUT_TYPE),hg)
-L10N_CO = $(PYTHON3) $(moztopsrcdir)/comm/python/l10n/l10n_clone/l10n_clone.py $(AB_CD) $(L10NBASEDIR)
+L10N_CO = $(PYTHON3) $(topsrcdir)/comm/python/l10n/l10n_clone/l10n_clone.py $(AB_CD) $(L10NBASEDIR)
 else
 L10N_CO = $(error You need to use hg)
 endif
@@ -98,11 +98,11 @@ endif
 
 ident:
 	@printf 'comm_revision '
-	@$(PYTHON3) $(moztopsrcdir)/config/printconfigsetting.py \
+	@$(PYTHON3) $(topsrcdir)/config/printconfigsetting.py \
 	    '$(STAGEDIST)/application.ini' App SourceStamp
 	@printf 'moz_revision '
-	@$(PYTHON3) $(moztopsrcdir)/config/printconfigsetting.py \
+	@$(PYTHON3) $(topsrcdir)/config/printconfigsetting.py \
 	    '$(STAGEDIST)/platform.ini' Build SourceStamp
 	@printf 'buildid '
-	@$(PYTHON3) $(moztopsrcdir)/config/printconfigsetting.py \
+	@$(PYTHON3) $(topsrcdir)/config/printconfigsetting.py \
 	    '$(STAGEDIST)/application.ini' App BuildID
diff --git a/third_party/Makefile.in b/third_party/Makefile.in
index 64d65286b7..fc5e8d2440 100644
--- a/third_party/Makefile.in
+++ b/third_party/Makefile.in
@@ -3,8 +3,8 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 
-include $(moztopsrcdir)/config/config.mk
-include $(moztopsrcdir)/config/rules.mk
+include $(topsrcdir)/config/config.mk
+include $(topsrcdir)/config/rules.mk
 
 print-%: ; @echo $* is $($*)
 origin-%: ; @echo $* origin $(origin $*)
diff --git a/third_party/botan/Makefile.in b/third_party/botan/Makefile.in
index 7a0e83c50c..2aaf56941f 100644
--- a/third_party/botan/Makefile.in
+++ b/third_party/botan/Makefile.in
@@ -2,7 +2,7 @@
 # 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/.
 
-include $(moztopsrcdir)/config/config.mk
+include $(topsrcdir)/config/config.mk
 include $(topsrcdir)/config/rules.mk
 
 ifdef COMPILE_ENVIRONMENT