Index: packages/Python/lldbsuite/test/tools/lldb-mi/syntax/TestMiSyntax.py
===================================================================
--- packages/Python/lldbsuite/test/tools/lldb-mi/syntax/TestMiSyntax.py
+++ packages/Python/lldbsuite/test/tools/lldb-mi/syntax/TestMiSyntax.py
@@ -84,3 +84,79 @@
         # Test that a process output is wrapped correctly
         self.expect("\@\"'\\\\r\\\\n\"")
         self.expect("\@\"` - it's \\\\\\\\n\\\\x12\\\\\"\\\\\\\\\\\\\"")
+
+    @skipIfWindows  # llvm.org/pr24452: Get lldb-mi tests working on Windows
+    @skipIfFreeBSD  # llvm.org/pr22411: Failure presumably due to known thread races
+    def test_lldbmi_output_grammar(self):
+        """Test that 'lldb-mi --interpreter' uses standard output syntax."""
+
+        self.spawnLldbMi(args = None)
+        self.child.setecho(False)
+
+        # Run all commands simultaneously
+        self.runCmd("-unknown-command")
+        self.runCmd("-file-exec-and-symbols %s" % self.myexe)
+        self.runCmd("-break-insert -f main")
+        self.runCmd("-gdb-set target-async off")
+        self.runCmd("-exec-run")
+        self.runCmd("-gdb-set target-async on")
+        self.runCmd("-exec-continue")
+        self.runCmd("-gdb-exit")
+
+        # Test that the program's output matches to the following pattern:
+        # ( async-record | stream-record )* [ result-record ] "(gdb)" nl
+        async_record  = "^[0-9]*(\*|\+|=).+?\n" # 1
+        stream_record = "^(~|@|&).+?\n"         # 2
+        result_record = "^[0-9]*\^.+?\n"        # 3
+        prompt        = "^\(gdb\)\r\n"          # 4
+        command       = "^\r\n"                 # 5 (it looks like empty line for pexpect)
+        error         = "^.+?\n"                # 6
+        import pexpect                          # 7 (EOF)
+        all_patterns = [ async_record, stream_record, result_record, prompt, command, error, pexpect.EOF ]
+        def get_bit(pattern):  return all_patterns.index(pattern)
+        def get_mask(pattern): return 1 << get_bit(pattern)
+        def or_op(x, y):       return x | y
+        def get_state(*args):  return reduce(or_op, map(get_mask, args))
+
+        next_state = get_state(command)
+        while True:
+            it = self.expect(all_patterns)
+            matched_pattern = all_patterns[it]
+
+            # Check that state is acceptable
+            if not (next_state & get_mask(matched_pattern)):
+                self.fail("error: inconsistent pattern '%s' for state %#x (matched string: %s)" % (repr(matched_pattern), next_state, self.child.after))
+            elif matched_pattern == async_record or matched_pattern == stream_record:
+                next_state = get_state(async_record, stream_record, result_record, prompt)
+            elif matched_pattern == result_record:
+                # FIXME lldb-mi prints the async-record out of turn
+                # ```
+                #   ^done
+                #   (gdb)
+                #   ^running
+                #   =thread-group-started,id="i1",pid="13875"
+                #   (gdb)
+                # ```
+                # Therefore to pass that test I changed the grammar's rule:
+                #   next_state = get_state(prompt)
+                # to:
+                next_state = get_state(async_record, prompt)
+            elif matched_pattern == prompt:
+                # FIXME lldb-mi prints the prompt out of turn
+                # ```
+                #   ^done
+                #   (gdb)
+                #   ^running
+                #   (gdb)
+                #   (gdb)
+                # ```
+                # Therefore to pass that test I changed the grammar's rule:
+                #   next_state = get_state(async_record, stream_record, result_record, command, pexpect.EOF)
+                # to:
+                next_state = get_state(async_record, stream_record, result_record, prompt, command, pexpect.EOF)
+            elif matched_pattern == command:
+                next_state = get_state(async_record, stream_record, result_record)
+            elif matched_pattern == pexpect.EOF:
+                break
+            else:
+                self.fail("error: pexpect returned an unknown state")
Index: tools/lldb-mi/MIDriver.cpp
===================================================================
--- tools/lldb-mi/MIDriver.cpp
+++ tools/lldb-mi/MIDriver.cpp
@@ -602,9 +602,6 @@
   // Close and wait for the workers to stop
   StopWorkerThreads();
 
-  // Ensure that a new line is sent as the last act of the dying driver
-  m_rStdOut.WriteMIResponse("\n", false);
-
   return MIstatus::success;
 }