diff --git a/llvm/utils/chunk-print-before-all.py b/llvm/utils/chunk-print-before-all.py
--- a/llvm/utils/chunk-print-before-all.py
+++ b/llvm/utils/chunk-print-before-all.py
@@ -1,21 +1,26 @@
 #!/usr/bin/env python
-# Given a -print-before-all -print-module-scope log from an opt invocation,
-# chunk it into a series of individual IR files, one for each pass invocation.
-# If the log ends with an obvious stack trace, try to split off a separate
-# "crashinfo.txt" file leaving only the valid input IR in the last chunk.
-# Files are written to current working directory.
 
-from __future__ import print_function
+# Given a -print-before-all and/or -print-after-all -print-module-scope log from 
+# an opt invocation, chunk it into a series of individual IR files, one for each 
+# pass invocation. If the log ends with an obvious stack trace, try to split off 
+# a separate "crashinfo.txt" file leaving only the valid input IR in the last 
+# chunk. Files are written to current working directory.
 
 import sys
 
-basename = "chunk-"
 chunk_id = 0
 
-def print_chunk(lines):
+def get_pass_name(line, prefix):
+    short_line = line[line.find(prefix) + len(prefix) + 1:]
+    if  short_line.find("<") == -1 or \
+        short_line.find("<") > short_line.find(" "):
+        return short_line[:short_line.find(" ")]
+    else:
+        return short_line[:short_line.find("<")]
+
+def print_chunk(lines, prefix, pass_name):
     global chunk_id
-    global basename
-    fname = basename + str(chunk_id) + ".ll"
+    fname = str(chunk_id) + "-" + prefix + "-" + pass_name + ".ll"
     chunk_id = chunk_id + 1
     print("writing chunk " + fname + " (" + str(len(lines)) + " lines)")
     with open(fname, "w") as f:
@@ -26,11 +31,18 @@
 for line in sys.stdin:
     if line.startswith("*** IR Dump Before "):
         if len(cur) != 0:
-            print_chunk(cur);
+            print_chunk(cur, "before", pass_name)
+            cur = []
+        cur.append("; " + line)
+        pass_name = get_pass_name(line, "Before")
+    elif line.startswith("*** IR Dump After "):
+        if len(cur) != 0:
+            print_chunk(cur, "after", pass_name)
             cur = []
         cur.append("; " + line)
+        pass_name = get_pass_name(line, "After")
     elif line.startswith("Stack dump:"):
-        print_chunk(cur);
+        print_chunk(cur, "crash", pass_name)
         cur = []
         cur.append(line)
         is_dump = True
@@ -42,4 +54,4 @@
     with open("crashinfo.txt", "w") as f:
         f.writelines(cur)
 else:
-    print_chunk(cur);
+    print_chunk(cur, "last", pass_name)