diff --git a/client.mk b/client.mk
index 1fdcc2aa9ce6..60d4112d3d3c 100644
--- a/client.mk
+++ b/client.mk
@@ -457,6 +457,7 @@ ifndef MAKE
 MAKE := gmake
 endif
 PERL ?= perl
+PYTHON ?= python
 
 CONFIG_GUESS_SCRIPT := $(wildcard $(TOPSRCDIR)/build/autoconf/config.guess)
 ifdef CONFIG_GUESS_SCRIPT
@@ -940,7 +941,7 @@ else
 ifdef MOZ_UNIFY_BDATE
 ifndef MOZ_BUILD_DATE
 ifdef MOZ_BUILD_PROJECTS
-MOZ_BUILD_DATE = $(shell $(PERL) -I$(TOPSRCDIR)/config $(TOPSRCDIR)/config/bdate.pl)
+MOZ_BUILD_DATE = $(shell $(PYTHON) $(TOPSRCDIR)/toolkit/xre/make-platformini.py --print-buildid)
 export MOZ_BUILD_DATE
 endif
 endif
diff --git a/toolkit/xre/make-platformini.py b/toolkit/xre/make-platformini.py
index 78c5d91cb0fa..4e2a904d53d8 100644
--- a/toolkit/xre/make-platformini.py
+++ b/toolkit/xre/make-platformini.py
@@ -3,9 +3,19 @@
 from optparse import OptionParser
 from datetime import datetime
 import sys
+import os
 
-(milestoneFile,) = sys.argv[1:]
+o = OptionParser()
+o.add_option("--print-buildid", action="store_true", dest="print_buildid")
 
+(options, args) = o.parse_args()
+buildid = os.environ.get('MOZ_BUILD_DATE', datetime.now().strftime('%Y%m%d%H'))
+
+if options.print_buildid:
+    print buildid
+    sys.exit(0)
+
+(milestoneFile,) = args
 for line in open(milestoneFile, 'r'):
     if line[0] == '#':
         continue
@@ -18,4 +28,4 @@ for line in open(milestoneFile, 'r'):
 
 print """[Build]
 BuildID=%s
-Milestone=%s""" % (datetime.now().strftime('%Y%m%d%H'), milestone)
+Milestone=%s""" % (buildid, milestone)