Index: lldb/include/lldb/Interpreter/CommandCompletions.h
===================================================================
--- lldb/include/lldb/Interpreter/CommandCompletions.h
+++ lldb/include/lldb/Interpreter/CommandCompletions.h
@@ -46,10 +46,11 @@
     eStopHookIDCompletion = (1u << 18),
     eTypeCategoryNameCompletion = (1u << 19),
     eTypeLanguageCompletion = (1u << 20),
+    eDisassemblyFlavorCompletion = (1u << 21),
     // This item serves two purposes.  It is the last element in the enum, so
     // you can add custom enums starting from here in your Option class. Also
     // if you & in this bit the base code will not process the option.
-    eCustomCompletion = (1u << 21)
+    eCustomCompletion = (1u << 22)
   };
 
   static bool InvokeCommonCompletionCallbacks(
@@ -132,6 +133,10 @@
 
   static void TypeLanguages(CommandInterpreter &interpreter,
                             CompletionRequest &request, SearchFilter *searcher);
+
+  static void DisassemblyFlavors(CommandInterpreter &interpreter,
+                                 CompletionRequest &request,
+                                 SearchFilter *searcher);
 };
 
 } // namespace lldb_private
Index: lldb/source/Commands/CommandCompletions.cpp
===================================================================
--- lldb/source/Commands/CommandCompletions.cpp
+++ lldb/source/Commands/CommandCompletions.cpp
@@ -73,6 +73,7 @@
       {eStopHookIDCompletion, CommandCompletions::StopHookIDs},
       {eTypeCategoryNameCompletion, CommandCompletions::TypeCategoryNames},
       {eTypeLanguageCompletion, CommandCompletions::TypeLanguages},
+      {eDisassemblyFlavorCompletion, CommandCompletions::DisassemblyFlavors},
       {eNoCompletion, nullptr} // This one has to be last in the list.
   };
 
@@ -753,3 +754,14 @@
         Language::GetNameForLanguageType((lldb::LanguageType)bit));
   }
 }
+
+void CommandCompletions::DisassemblyFlavors(CommandInterpreter &interpreter,
+                                            CompletionRequest &request,
+                                            SearchFilter *searcher) {
+  // Currently the only valid options for disassemble -F are default, and for
+  // Intel architectures, att and intel.
+  static const char *flavors[] = {"default", "att", "intel"};
+  for (const char *flavor : flavors) {
+    request.TryCompleteCurrentArg(flavor);
+  }
+}
Index: lldb/source/Interpreter/CommandObject.cpp
===================================================================
--- lldb/source/Interpreter/CommandObject.cpp
+++ lldb/source/Interpreter/CommandObject.cpp
@@ -1047,7 +1047,7 @@
     { eArgTypeCommandName, "cmd-name", CommandCompletions::eNoCompletion, { nullptr, false }, "A debugger command (may be multiple words), without any options or arguments." },
     { eArgTypeCount, "count", CommandCompletions::eNoCompletion, { nullptr, false }, "An unsigned integer." },
     { eArgTypeDirectoryName, "directory", CommandCompletions::eDiskDirectoryCompletion, { nullptr, false }, "A directory name." },
-    { eArgTypeDisassemblyFlavor, "disassembly-flavor", CommandCompletions::eNoCompletion, { nullptr, false }, "A disassembly flavor recognized by your disassembly plugin.  Currently the only valid options are \"att\" and \"intel\" for Intel targets" },
+    { eArgTypeDisassemblyFlavor, "disassembly-flavor", CommandCompletions::eDisassemblyFlavorCompletion, { nullptr, false }, "A disassembly flavor recognized by your disassembly plugin.  Currently the only valid options are \"att\" and \"intel\" for Intel targets" },
     { eArgTypeDescriptionVerbosity, "description-verbosity", CommandCompletions::eNoCompletion, { nullptr, false }, "How verbose the output of 'po' should be." },
     { eArgTypeEndAddress, "end-address", CommandCompletions::eNoCompletion, { nullptr, false }, "Help text goes here." },
     { eArgTypeExpression, "expr", CommandCompletions::eNoCompletion, { nullptr, false }, "Help text goes here." },
Index: lldb/test/API/functionalities/completion/TestCompletion.py
===================================================================
--- lldb/test/API/functionalities/completion/TestCompletion.py
+++ lldb/test/API/functionalities/completion/TestCompletion.py
@@ -128,6 +128,12 @@
                                 '--thread-index',
                                 '--thread-name'])
 
+    def test_disassemble_dash_f(self):
+        self.completions_match('disassemble -F ',
+                               ['default',
+                                'intel',
+                                'att'])
+
     def test_plugin_load(self):
         self.complete_from_to('plugin load ', [])