diff --git a/lldb/source/API/SBDebugger.cpp b/lldb/source/API/SBDebugger.cpp
--- a/lldb/source/API/SBDebugger.cpp
+++ b/lldb/source/API/SBDebugger.cpp
@@ -1278,8 +1278,7 @@
       ConstString(debugger_instance_name)));
   Status error;
   if (debugger_sp) {
-    ExecutionContext exe_ctx(
-        debugger_sp->GetCommandInterpreter().GetExecutionContext());
+    ExecutionContext exe_ctx(debugger_sp->GetSelectedExecutionContext());
     error = debugger_sp->SetPropertyValue(&exe_ctx, eVarSetOperationAssign,
                                           var_name, value);
   } else {
@@ -1303,8 +1302,7 @@
       ConstString(debugger_instance_name)));
   Status error;
   if (debugger_sp) {
-    ExecutionContext exe_ctx(
-        debugger_sp->GetCommandInterpreter().GetExecutionContext());
+    ExecutionContext exe_ctx(debugger_sp->GetSelectedExecutionContext());
     lldb::OptionValueSP value_sp(
         debugger_sp->GetPropertyValue(&exe_ctx, var_name, false, error));
     if (value_sp) {
diff --git a/lldb/test/API/python_api/debugger/TestDebuggerAPI.py b/lldb/test/API/python_api/debugger/TestDebuggerAPI.py
--- a/lldb/test/API/python_api/debugger/TestDebuggerAPI.py
+++ b/lldb/test/API/python_api/debugger/TestDebuggerAPI.py
@@ -43,3 +43,35 @@
         target = lldb.SBTarget()
         self.assertFalse(target.IsValid())
         self.dbg.DeleteTarget(target)
+
+    @add_test_categories(['pyapi'])
+    def test_debugger_internal_variables(self):
+        debugger_name = self.dbg.GetInstanceName()
+
+        # Set a variable and check it was written successfully.
+        error = lldb.SBDebugger.SetInternalVariable(
+            'target.prefer-dynamic-value', 'no-dynamic-values', debugger_name)
+        self.assertTrue(error.Success())
+        ret = lldb.SBDebugger.GetInternalVariableValue(
+            'target.prefer-dynamic-value', debugger_name)
+        self.assertEqual(ret.GetSize(), 1)
+        self.assertEqual(ret.GetStringAtIndex(0), 'no-dynamic-values')
+
+        # Set a variable with a different value.
+        error = lldb.SBDebugger.SetInternalVariable(
+            'target.prefer-dynamic-value', 'no-run-target', debugger_name)
+        self.assertTrue(error.Success())
+        ret = lldb.SBDebugger.GetInternalVariableValue(
+            'target.prefer-dynamic-value', debugger_name)
+        self.assertEqual(ret.GetSize(), 1)
+        self.assertEqual(ret.GetStringAtIndex(0), 'no-run-target')
+
+        # Try setting invalid value, check for error.
+        error = lldb.SBDebugger.SetInternalVariable(
+            'target.prefer-dynamic-value', 'dummy-value', debugger_name)
+        self.assertTrue(error.Fail())
+        # Check that the value didn't change.
+        ret = lldb.SBDebugger.GetInternalVariableValue(
+            'target.prefer-dynamic-value', debugger_name)
+        self.assertEqual(ret.GetSize(), 1)
+        self.assertEqual(ret.GetStringAtIndex(0), 'no-run-target')