diff --git a/llvm/utils/lit/lit/TestRunner.py b/llvm/utils/lit/lit/TestRunner.py
index 068e4991b211..3c658eafcd9c 100644
--- a/llvm/utils/lit/lit/TestRunner.py
+++ b/llvm/utils/lit/lit/TestRunner.py
@@ -305,24 +305,57 @@ def isExpectedFail(test, xfails):
 
     return False
 
-def parseIntegratedTestScriptCommands(sourcepath):
+def parseIntegratedTestScriptCommands(source_path):
     """
     parseIntegratedTestScriptCommands(source_path) -> commands
 
     Parse the commands in an integrated test script file into a list of
     (line_number, command_type, line).
     """
-    line_number = 0
-    for ln in open(sourcepath):
-        line_number += 1
-        if 'RUN:' in ln:
-            yield (line_number, 'RUN', ln[ln.index('RUN:')+4:])
-        elif 'XFAIL:' in ln:
-            yield (line_number, 'XFAIL', ln[ln.index('XFAIL:') + 6:])
-        elif 'REQUIRES:' in ln:
-            yield (line_number, 'REQUIRES', ln[ln.index('REQUIRES:') + 9:])
-        elif 'END.' in ln:
-            yield (line_number, 'END', ln[ln.index('END.') + 4:])
+
+    # This code is carefully written to be dual compatible with Python 2.5+ and
+    # Python 3 without requiring input files to always have valid codings. The
+    # trick we use is to open the file in binary mode and use the regular
+    # expression library to find the commands, with it scanning strings in
+    # Python2 and bytes in Python3.
+    #
+    # Once we find a match, we do require each script line to be decodable to
+    # ascii, so we convert the outputs to ascii before returning. This way the
+    # remaining code can work with "strings" agnostic of the executing Python
+    # version.
+    
+    def to_bytes(str):
+        # Encode to Latin1 to get binary data.
+        return str.encode('ISO-8859-1')
+    keywords = ('RUN:', 'XFAIL:', 'REQUIRES:', 'END.')
+    keywords_re = re.compile(
+        to_bytes("(%s)(.*)\n" % ("|".join(k for k in keywords),)))
+
+    f = open(source_path, 'rb')
+    try:
+        # Read the entire file contents.
+        data = f.read()
+
+        # Iterate over the matches.
+        line_number = 1
+        last_match_position = 0
+        for match in keywords_re.finditer(data):
+            # Compute the updated line number by counting the intervening
+            # newlines.
+            match_position = match.start()
+            line_number += data.count(to_bytes('\n'), last_match_position,
+                                      match_position)
+            last_match_position = match_position
+
+            # Convert the keyword and line to ascii strings and yield the
+            # command. Note that we take care to return regular strings in
+            # Python 2, to avoid other code having to differentiate between the
+            # str and unicode types.
+            keyword,ln = match.groups()
+            yield (line_number, str(keyword[:-1].decode('ascii')),
+                   str(ln.decode('ascii')))
+    finally:
+        f.close()
 
 def parseIntegratedTestScript(test, normalize_slashes=False,
                               extra_substitutions=[]):
diff --git a/llvm/utils/lit/tests/shtest-encoding.py b/llvm/utils/lit/tests/shtest-encoding.py
new file mode 100644
index 000000000000..dfc987f6df7e
--- /dev/null
+++ b/llvm/utils/lit/tests/shtest-encoding.py
@@ -0,0 +1,3 @@
+# RUN: true
+
+# Here is a string that cannot be decoded in line mode: Â.