diff --git a/compiler-rt/test/lit.common.cfg.py b/compiler-rt/test/lit.common.cfg.py
index 6f325013a22ce..efd64b3ca9f96 100644
--- a/compiler-rt/test/lit.common.cfg.py
+++ b/compiler-rt/test/lit.common.cfg.py
@@ -181,7 +181,7 @@
   config.compile_wrapper = compile_wrapper
 
   try:
-    prepare_output = subprocess.check_output([prepare_script, config.apple_platform, config.clang]).strip()
+    prepare_output = subprocess.check_output([prepare_script, config.apple_platform, config.clang]).decode().strip()
   except subprocess.CalledProcessError as e:
     print("Command failed:")
     print(e.output)