Index: lldb/include/lldb/Interpreter/CommandInterpreter.h
===================================================================
--- lldb/include/lldb/Interpreter/CommandInterpreter.h
+++ lldb/include/lldb/Interpreter/CommandInterpreter.h
@@ -498,6 +498,14 @@
     return m_user_dict;
   }
 
+  const CommandObject::CommandMap &GetCommands() const {
+    return m_command_dict;
+  }
+
+  const CommandObject::CommandMap &GetAliases() const {
+    return m_alias_dict;
+  }
+
   /// Specify if the command interpreter should allow that the user can
   /// specify a custom exit code when calling 'quit'.
   void AllowExitCodeOnQuit(bool allow);
Index: lldb/source/Commands/CommandObjectCommands.cpp
===================================================================
--- lldb/source/Commands/CommandObjectCommands.cpp
+++ lldb/source/Commands/CommandObjectCommands.cpp
@@ -767,6 +767,19 @@
 
   ~CommandObjectCommandsUnalias() override = default;
 
+  void
+  HandleArgumentCompletion(CompletionRequest &request,
+                           OptionElementVector &opt_element_vector) override {
+
+    if (!m_interpreter.HasCommands() || request.GetCursorIndex() != 0)
+      return;
+    const auto &alias_dict = m_interpreter.GetAliases();
+
+    for (auto pos = alias_dict.begin(); pos != alias_dict.end(); ++pos) {
+      request.TryCompleteCurrentArg(pos->first, pos->second->GetHelp());
+    }
+  }
+
 protected:
   bool DoExecute(Args &args, CommandReturnObject &result) override {
     CommandObject::CommandMap::iterator pos;
@@ -848,6 +861,20 @@
 
   ~CommandObjectCommandsDelete() override = default;
 
+  void
+  HandleArgumentCompletion(CompletionRequest &request,
+                           OptionElementVector &opt_element_vector) override {
+
+    if (!m_interpreter.HasCommands() || request.GetCursorIndex() != 0)
+      return;
+    const auto &cmd_dict = m_interpreter.GetCommands();
+
+    for (auto pos = cmd_dict.begin(); pos != cmd_dict.end(); ++pos) {
+      if(pos->second->IsRemovable())
+        request.TryCompleteCurrentArg(pos->first, pos->second->GetHelp());
+    }
+  }
+
 protected:
   bool DoExecute(Args &args, CommandReturnObject &result) override {
     CommandObject::CommandMap::iterator pos;
Index: lldb/test/API/functionalities/completion/TestCompletion.py
===================================================================
--- lldb/test/API/functionalities/completion/TestCompletion.py
+++ lldb/test/API/functionalities/completion/TestCompletion.py
@@ -375,6 +375,13 @@
         self.runCmd("command script add -h test_desc -f none -s current usercmd1")
         self.check_completion_with_desc('command script delete ', [['usercmd1', 'test_desc']])
 
+    def test_command_delete(self):
+        self.runCmd(r"command regex f s/^$/finish/ 's/([0-9]+)/frame select %1/'")
+        self.complete_from_to('command delete ', ['f'])
+
+    def test_command_unalias(self):
+        self.complete_from_to('command unalias ima', 'command unalias image')
+
     def test_completion_description_commands(self):
         """Test descriptions of top-level command completions"""
         self.check_completion_with_desc("", [