Index: utils/lit/lit/util.py
===================================================================
--- utils/lit/lit/util.py
+++ utils/lit/lit/util.py
@@ -16,6 +16,12 @@
         return bytes
     return to_bytes(bytes)
 
+def convert_string(bytes):
+    try:
+        return to_string(bytes.decode('utf-8'))
+    except UnicodeError:
+        return str(bytes)
+
 def detectCPUs():
     """
     Detects the number of CPUs on a system. Cribbed from pp.
@@ -60,7 +66,7 @@
     p = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                          env=env)
     out,_ = p.communicate()
-    return out
+    return convert_string(out)
 
 def which(command, paths = None):
     """which(command, [paths]) - Look up the given command in the paths string
@@ -166,14 +172,8 @@
         raise KeyboardInterrupt
 
     # Ensure the resulting output is always of string type.
-    try:
-        out = to_string(out.decode('utf-8'))
-    except:
-        out = str(out)
-    try:
-        err = to_string(err.decode('utf-8'))
-    except:
-        err = str(err)
+    out = convert_string(out)
+    err = convert_string(err)
 
     return out, err, exitCode