diff --git a/lldb/include/lldb/Interpreter/CommandInterpreter.h b/lldb/include/lldb/Interpreter/CommandInterpreter.h
--- a/lldb/include/lldb/Interpreter/CommandInterpreter.h
+++ b/lldb/include/lldb/Interpreter/CommandInterpreter.h
@@ -501,6 +501,12 @@
     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);
diff --git a/lldb/source/Commands/CommandObjectCommands.cpp b/lldb/source/Commands/CommandObjectCommands.cpp
--- a/lldb/source/Commands/CommandObjectCommands.cpp
+++ b/lldb/source/Commands/CommandObjectCommands.cpp
@@ -618,6 +618,17 @@
 
   ~CommandObjectCommandsUnalias() override = default;
 
+  void
+  HandleArgumentCompletion(CompletionRequest &request,
+                           OptionElementVector &opt_element_vector) override {
+    if (!m_interpreter.HasCommands() || request.GetCursorIndex() != 0)
+      return;
+
+    for (const auto &ent : m_interpreter.GetAliases()) {
+      request.TryCompleteCurrentArg(ent.first, ent.second->GetHelp());
+    }
+  }
+
 protected:
   bool DoExecute(Args &args, CommandReturnObject &result) override {
     CommandObject::CommandMap::iterator pos;
@@ -699,6 +710,18 @@
 
   ~CommandObjectCommandsDelete() override = default;
 
+  void
+  HandleArgumentCompletion(CompletionRequest &request,
+                           OptionElementVector &opt_element_vector) override {
+    if (!m_interpreter.HasCommands() || request.GetCursorIndex() != 0)
+      return;
+
+    for (const auto &ent : m_interpreter.GetCommands()) {
+      if (ent.second->IsRemovable())
+        request.TryCompleteCurrentArg(ent.first, ent.second->GetHelp());
+    }
+  }
+
 protected:
   bool DoExecute(Args &args, CommandReturnObject &result) override {
     CommandObject::CommandMap::iterator pos;
diff --git a/lldb/test/API/functionalities/completion/TestCompletion.py b/lldb/test/API/functionalities/completion/TestCompletion.py
--- a/lldb/test/API/functionalities/completion/TestCompletion.py
+++ b/lldb/test/API/functionalities/completion/TestCompletion.py
@@ -401,6 +401,13 @@
         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 test_command s/^$/finish/ 's/([0-9]+)/frame select %1/'")
+        self.complete_from_to('command delete test_c', 'command delete test_command')
+
+    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("", [