Index: cfe/trunk/tools/scan-build-py/libscanbuild/report.py
===================================================================
--- cfe/trunk/tools/scan-build-py/libscanbuild/report.py
+++ cfe/trunk/tools/scan-build-py/libscanbuild/report.py
@@ -21,6 +21,7 @@
 import json
 import logging
 import contextlib
+import datetime
 from libscanbuild import duplicate_check
 from libscanbuild.clang import get_version
 
@@ -34,7 +35,8 @@
     hint -- could specify the parent directory of the output directory.
     keep -- a boolean value to keep or delete the empty report directory. """
 
-    stamp = time.strftime('scan-build-%Y-%m-%d-%H%M%S-', time.localtime())
+    stamp_format = 'scan-build-%Y-%m-%d-%H-%M-%S-%f-'
+    stamp = datetime.datetime.now().strftime(stamp_format)
 
     parentdir = os.path.abspath(hint)
     if not os.path.exists(parentdir):
Index: cfe/trunk/tools/scan-build-py/tests/unit/test_report.py
===================================================================
--- cfe/trunk/tools/scan-build-py/tests/unit/test_report.py
+++ cfe/trunk/tools/scan-build-py/tests/unit/test_report.py
@@ -146,3 +146,16 @@
     def test_empty(self):
         self.assertEqual(
             sut.commonprefix([]), '')
+
+class ReportDirectoryTest(unittest.TestCase):
+
+    # Test that successive report directory names ascend in lexicographic
+    # order. This is required so that report directories from two runs of
+    # scan-build can be easily matched up to compare results.
+    def test_directory_name_comparison(self):
+        with libear.TemporaryDirectory() as tmpdir, \
+             sut.report_directory(tmpdir, False) as report_dir1, \
+             sut.report_directory(tmpdir, False) as report_dir2, \
+             sut.report_directory(tmpdir, False) as report_dir3:
+            self.assertLess(report_dir1, report_dir2)
+            self.assertLess(report_dir2, report_dir3)