Index: lldb/trunk/include/lldb/Core/ModuleList.h
===================================================================
--- lldb/trunk/include/lldb/Core/ModuleList.h
+++ lldb/trunk/include/lldb/Core/ModuleList.h
@@ -52,6 +52,7 @@
   FileSpec GetClangModulesCachePath() const;
   bool SetClangModulesCachePath(llvm::StringRef path);
   bool GetEnableExternalLookup() const;
+  bool SetEnableExternalLookup(bool new_value);
 }; 
 
 /// \class ModuleList ModuleList.h "lldb/Core/ModuleList.h"
Index: lldb/trunk/lit/tools/lldb-mi/breakpoint/break-insert-enable-pending.test
===================================================================
--- lldb/trunk/lit/tools/lldb-mi/breakpoint/break-insert-enable-pending.test
+++ lldb/trunk/lit/tools/lldb-mi/breakpoint/break-insert-enable-pending.test
@@ -7,6 +7,9 @@
 
 # Test for enabling pending breakpoints globally
 
+settings set symbols.enable-external-lookup false
+# CHECK: ^done
+
 -break-insert printf
 # CHECK: ^error,msg="Command 'break-insert'. Breakpoint location 'printf' not found
 
Index: lldb/trunk/lit/tools/lldb-mi/breakpoint/break-insert.test
===================================================================
--- lldb/trunk/lit/tools/lldb-mi/breakpoint/break-insert.test
+++ lldb/trunk/lit/tools/lldb-mi/breakpoint/break-insert.test
@@ -6,6 +6,9 @@
 
 # Test that a breakpoint can be inserted before creating a target.
 
+settings set symbols.enable-external-lookup false
+# CHECK: ^done
+
 -break-insert breakpoint
 # CHECK: ^done,bkpt={number="1"
 
Index: lldb/trunk/lit/tools/lldb-mi/data/data-info-line.test
===================================================================
--- lldb/trunk/lit/tools/lldb-mi/data/data-info-line.test
+++ lldb/trunk/lit/tools/lldb-mi/data/data-info-line.test
@@ -8,6 +8,9 @@
 # Check that we have a valid target created via '%lldbmi %t'.
 # CHECK: ^done
 
+settings set symbols.enable-external-lookup false
+# CHECK: ^done
+
 -break-insert main
 # CHECK: ^done,bkpt={number="1"
 
Index: lldb/trunk/lit/tools/lldb-mi/exec/exec-continue.test
===================================================================
--- lldb/trunk/lit/tools/lldb-mi/exec/exec-continue.test
+++ lldb/trunk/lit/tools/lldb-mi/exec/exec-continue.test
@@ -8,6 +8,9 @@
 # Check that we have a valid target created via '%lldbmi %t'.
 # CHECK: ^done
 
+settings set symbols.enable-external-lookup false
+# CHECK: ^done
+
 -break-insert main
 # CHECK: ^done,bkpt={number="1"
 
Index: lldb/trunk/lit/tools/lldb-mi/exec/exec-finish.test
===================================================================
--- lldb/trunk/lit/tools/lldb-mi/exec/exec-finish.test
+++ lldb/trunk/lit/tools/lldb-mi/exec/exec-finish.test
@@ -6,6 +6,9 @@
 # Check that we have a valid target created via '%lldbmi %t'.
 # CHECK: ^done
 
+settings set symbols.enable-external-lookup false
+# CHECK: ^done
+
 -break-insert main
 # CHECK: ^done,bkpt={number="1"
 
Index: lldb/trunk/lit/tools/lldb-mi/exec/exec-interrupt.test
===================================================================
--- lldb/trunk/lit/tools/lldb-mi/exec/exec-interrupt.test
+++ lldb/trunk/lit/tools/lldb-mi/exec/exec-interrupt.test
@@ -8,6 +8,9 @@
 # Check that we have a valid target created via '%lldbmi %t'.
 # CHECK: ^done
 
+settings set symbols.enable-external-lookup false
+# CHECK: ^done
+
 -break-insert main
 # CHECK: ^done,bkpt={number="1"
 
Index: lldb/trunk/lit/tools/lldb-mi/exec/exec-next-instruction.test
===================================================================
--- lldb/trunk/lit/tools/lldb-mi/exec/exec-next-instruction.test
+++ lldb/trunk/lit/tools/lldb-mi/exec/exec-next-instruction.test
@@ -8,6 +8,9 @@
 # Check that we have a valid target created via '%lldbmi %t'.
 # CHECK: ^done
 
+settings set symbols.enable-external-lookup false
+# CHECK: ^done
+
 -break-insert main
 # CHECK: ^done,bkpt={number="1"
 
Index: lldb/trunk/lit/tools/lldb-mi/exec/exec-next.test
===================================================================
--- lldb/trunk/lit/tools/lldb-mi/exec/exec-next.test
+++ lldb/trunk/lit/tools/lldb-mi/exec/exec-next.test
@@ -9,6 +9,9 @@
 # Check that we have a valid target created via '%lldbmi %t'.
 # CHECK: ^done
 
+settings set symbols.enable-external-lookup false
+# CHECK: ^done
+
 -break-insert main
 # CHECK: ^done,bkpt={number="1"
 
Index: lldb/trunk/lit/tools/lldb-mi/exec/exec-step-instruction.test
===================================================================
--- lldb/trunk/lit/tools/lldb-mi/exec/exec-step-instruction.test
+++ lldb/trunk/lit/tools/lldb-mi/exec/exec-step-instruction.test
@@ -8,6 +8,9 @@
 # Check that we have a valid target created via '%lldbmi %t'.
 # CHECK: ^done
 
+settings set symbols.enable-external-lookup false
+# CHECK: ^done
+
 -break-insert main
 # CHECK: ^done,bkpt={number="1"
 
Index: lldb/trunk/lit/tools/lldb-mi/exec/exec-step.test
===================================================================
--- lldb/trunk/lit/tools/lldb-mi/exec/exec-step.test
+++ lldb/trunk/lit/tools/lldb-mi/exec/exec-step.test
@@ -8,6 +8,9 @@
 # Check that we have a valid target created via '%lldbmi %t'.
 # CHECK: ^done
 
+settings set symbols.enable-external-lookup false
+# CHECK: ^done
+
 -break-insert main
 # CHECK: ^done,bkpt={number="1"
 
Index: lldb/trunk/packages/Python/lldbsuite/test/api/multithreaded/driver.cpp.template
===================================================================
--- lldb/trunk/packages/Python/lldbsuite/test/api/multithreaded/driver.cpp.template
+++ lldb/trunk/packages/Python/lldbsuite/test/api/multithreaded/driver.cpp.template
@@ -31,6 +31,7 @@
 
   SBDebugger::Initialize();
   SBDebugger dbg = SBDebugger::Create();
+  dbg.HandleCommand("settings set symbols.enable-external-lookup false");
 
   try {
     if (!dbg.IsValid())
Index: lldb/trunk/packages/Python/lldbsuite/test/lldbtest.py
===================================================================
--- lldb/trunk/packages/Python/lldbsuite/test/lldbtest.py
+++ lldb/trunk/packages/Python/lldbsuite/test/lldbtest.py
@@ -729,12 +729,12 @@
         else:
             self.lldbVSCodeExec = None
 
+        self.lldbOption = "-o 'settings set symbols.enable-external-lookup false'"
+
         # If we spawn an lldb process for test (via pexpect), do not load the
         # init file unless told otherwise.
-        if "NO_LLDBINIT" in os.environ and "NO" == os.environ["NO_LLDBINIT"]:
-            self.lldbOption = ""
-        else:
-            self.lldbOption = "--no-lldbinit"
+        if os.environ.get("NO_LLDBINIT") != "NO":
+            self.lldbOption += " --no-lldbinit"
 
         # Assign the test method name to self.testMethodName.
         #
Index: lldb/trunk/packages/Python/lldbsuite/test/tools/lldb-vscode/vscode.py
===================================================================
--- lldb/trunk/packages/Python/lldbsuite/test/tools/lldb-vscode/vscode.py
+++ lldb/trunk/packages/Python/lldbsuite/test/tools/lldb-vscode/vscode.py
@@ -447,8 +447,10 @@
             args_dict['waitFor'] = waitFor
         if trace:
             args_dict['trace'] = trace
+        args_dict['initCommands'] = [
+            'settings set symbols.enable-external-lookup false']
         if initCommands:
-            args_dict['initCommands'] = initCommands
+            args_dict['initCommands'].extend(initCommands)
         if preRunCommands:
             args_dict['preRunCommands'] = preRunCommands
         if stopCommands:
@@ -582,8 +584,10 @@
             args_dict['shellExpandArguments'] = shellExpandArguments
         if trace:
             args_dict['trace'] = trace
+        args_dict['initCommands'] = [
+            'settings set symbols.enable-external-lookup false']
         if initCommands:
-            args_dict['initCommands'] = initCommands
+            args_dict['initCommands'].extend(initCommands)
         if preRunCommands:
             args_dict['preRunCommands'] = preRunCommands
         if stopCommands:
Index: lldb/trunk/source/Core/ModuleList.cpp
===================================================================
--- lldb/trunk/source/Core/ModuleList.cpp
+++ lldb/trunk/source/Core/ModuleList.cpp
@@ -102,6 +102,11 @@
       nullptr, idx, g_properties[idx].default_uint_value != 0);
 }
 
+bool ModuleListProperties::SetEnableExternalLookup(bool new_value) {
+  return m_collection_sp->SetPropertyAtIndexAsBoolean(
+      nullptr, ePropertyEnableExternalLookup, new_value);
+}
+
 FileSpec ModuleListProperties::GetClangModulesCachePath() const {
   return m_collection_sp
       ->GetPropertyAtIndexAsOptionValueFileSpec(nullptr, false,
Index: lldb/trunk/tools/lldb-test/lldb-test.cpp
===================================================================
--- lldb/trunk/tools/lldb-test/lldb-test.cpp
+++ lldb/trunk/tools/lldb-test/lldb-test.cpp
@@ -975,6 +975,7 @@
   CleanUp TerminateDebugger([&] { DebuggerLifetime.Terminate(); });
 
   auto Dbg = lldb_private::Debugger::CreateInstance();
+  ModuleList::GetGlobalModuleListProperties().SetEnableExternalLookup(false);
 
   if (!opts::Log.empty())
     Dbg->EnableLog("lldb", {"all"}, opts::Log, 0, errs());