Index: lldb/test/API/lldbtest.py
===================================================================
--- lldb/test/API/lldbtest.py
+++ lldb/test/API/lldbtest.py
@@ -82,7 +82,7 @@
                     sys.executable,
                     '-c',
                     'import sys; print(sys.executable)'
-                ]).decode('utf-8').strip()
+                ]).decode('utf-8', errors="ignore").strip()
                 shutil.copy(python, copied_python)
             cmd[0] = copied_python
 
@@ -99,6 +99,10 @@
             timeoutInfo = 'Reached timeout of {} seconds'.format(
                 litConfig.maxIndividualTestTime)
 
+        # Decode stdout and stderr as it might contains UTF-8 characters.
+        out = out.decode("utf-8", errors="ignore")
+        err = err.decode("utf-8", errors="ignore")
+
         output = """Script:\n--\n%s\n--\nExit Code: %d\n""" % (
             ' '.join(cmd), exitCode)
         if timeoutInfo is not None: