Index: lldb/packages/Python/lldbsuite/test/lldbpexpect.py
===================================================================
--- lldb/packages/Python/lldbsuite/test/lldbpexpect.py
+++ lldb/packages/Python/lldbsuite/test/lldbpexpect.py
@@ -27,7 +27,8 @@
         def expect_prompt(self):
             self.child.expect_exact(self.PROMPT)
 
-        def launch(self, executable=None, extra_args=None, timeout=30, dimensions=None):
+        def launch(self, executable=None, extra_args=None, timeout=30, dimensions=None,
+                   term_env_var="vt100"):
             logfile = getattr(sys.stdout, 'buffer',
                               sys.stdout) if self.TraceOn() else None
 
@@ -40,7 +41,7 @@
                 args.extend(extra_args)
 
             env = dict(os.environ)
-            env["TERM"]="vt100"
+            env["TERM"]=term_env_var
 
             self.child = pexpect.spawn(
                     lldbtest_config.lldbExec, args=args, logfile=logfile,
Index: lldb/source/Core/IOHandler.cpp
===================================================================
--- lldb/source/Core/IOHandler.cpp
+++ lldb/source/Core/IOHandler.cpp
@@ -251,6 +251,9 @@
 
   use_editline = GetInputFILE() && GetOutputFILE() && GetErrorFILE() &&
                  m_input_sp && m_input_sp->GetIsRealTerminal();
+  // Don't use editline for dumb terms.
+  if (llvm::StringRef(getenv("TERM")) == "dumb")
+    use_editline = false;
 
   if (use_editline) {
     m_editline_up.reset(new Editline(editline_name, GetInputFILE(),
@@ -291,7 +294,8 @@
 
 void IOHandlerEditline::TerminalSizeChanged() {
 #if LLDB_ENABLE_LIBEDIT
-  m_editline_up->TerminalSizeChanged();
+  if (m_editline_up)
+    m_editline_up->TerminalSizeChanged();
 #endif
 }
 
Index: lldb/test/API/iohandler/sigwinch/TestIOHandlerSigwinch.py
===================================================================
--- /dev/null
+++ lldb/test/API/iohandler/sigwinch/TestIOHandlerSigwinch.py
@@ -0,0 +1,25 @@
+"""
+Test SIGWINCH handling.
+"""
+
+import os
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.lldbpexpect import PExpectTest
+
+class TestCase(PExpectTest):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    # PExpect uses many timeouts internally and doesn't play well
+    # under ASAN on a loaded machine..
+    @skipIfAsan
+    def test_sigwinch_dumb_term(self):
+        self.launch(term_env_var="dumb")
+        os.kill(self.child.pid, signal.SIGWINCH)
+        # Check that LLDB didn't crash.
+        self.expect("help", substrs=["Current command abbreviations"])
+
+        self.quit()