--- a/im/confvars.sh
+++ b/im/confvars.sh
@@ -16,16 +16,13 @@ MOZ_MEDIA_NAVIGATOR=1
 
 MOZ_APP_VERSION_TXT=${_topsrcdir}/$MOZ_BUILD_APP/config/version.txt
 MOZ_APP_VERSION=`cat $MOZ_APP_VERSION_TXT`
 INSTANTBIRD_VERSION=$MOZ_APP_VERSION
 
 MOZ_BRANDING_DIRECTORY=im/branding/nightly
 MOZ_OFFICIAL_BRANDING_DIRECTORY=other-licenses/branding/instantbird
 MOZ_APP_ID={33cb9019-c295-46dd-be21-8c4936574bee}
-if test "$OS_TARGET" = "WINNT" -o "$OS_TARGET" = "Darwin"; then
-  MOZ_FOLD_LIBS=1
-fi
 # Enable generational GC on desktop.
 JSGC_GENERATIONAL=1
 if test "$OS_TARGET" = "WINNT"; then
   NSS_EXTRA_SYMBOLS_FILE=../../../../chat/nss-purple.def
 fi

--- a/mail/confvars.sh
+++ b/mail/confvars.sh
@@ -35,13 +35,10 @@ MOZ_BRANDING_DIRECTORY=mail/branding/nig
 MOZ_OFFICIAL_BRANDING_DIRECTORY=other-licenses/branding/thunderbird
 MOZ_APP_ID={3550f703-e582-4d05-9a08-453d09bdfdc6}
 # This should usually be the same as the value MAR_CHANNEL_ID.
 # If more than one ID is needed, then you should use a comma separated list
 # of values.
 ACCEPTED_MAR_CHANNEL_IDS=thunderbird-comm-central
 # The MAR_CHANNEL_ID must not contain the following 3 characters: ",\t "
 MAR_CHANNEL_ID=thunderbird-comm-central
-if test "$OS_TARGET" = "WINNT" -o "$OS_TARGET" = "Darwin"; then
-  MOZ_FOLD_LIBS=1
-fi
 # Enable generational GC on desktop.
 JSGC_GENERATIONAL=1

--- a/suite/confvars.sh
+++ b/suite/confvars.sh
@@ -37,13 +37,10 @@ MOZ_APP_VERSION_TXT=${_topsrcdir}/$MOZ_B
 MOZ_APP_VERSION=`cat $MOZ_APP_VERSION_TXT`
 SEAMONKEY_VERSION=$MOZ_APP_VERSION
 
 MOZ_UA_BUILDID=20100101
 
 MOZ_APP_ID={92650c4d-4b8e-4d2a-b7eb-24ecf4f6b63a}
 MOZ_PROFILE_MIGRATOR=1
 MOZ_APP_STATIC_INI=1
-if test "$OS_TARGET" = "WINNT" -o "$OS_TARGET" = "Darwin"; then
-  MOZ_FOLD_LIBS=1
-fi
 # Enable generational GC on desktop.
 JSGC_GENERATIONAL=1