Index: packages/Python/lldbsuite/test/expression_command/completion-crash-lambda/TestCompletionCrashInLambda.py
===================================================================
--- packages/Python/lldbsuite/test/expression_command/completion-crash-lambda/TestCompletionCrashInLambda.py
+++ /dev/null
@@ -1,4 +0,0 @@
-from lldbsuite.test import lldbinline
-from lldbsuite.test import decorators
-
-lldbinline.MakeInlineTest(__file__, globals(), [decorators.skipIf(bugnumber="rdar://53755023")])
Index: packages/Python/lldbsuite/test/expression_command/completion-crash-lambda/main.cpp
===================================================================
--- packages/Python/lldbsuite/test/expression_command/completion-crash-lambda/main.cpp
+++ /dev/null
@@ -1,6 +0,0 @@
-int main() {
-  []()
-  { //%self.dbg.GetCommandInterpreter().HandleCompletion("e ", len("e "), 0, -1, lldb.SBStringList())
-  }
-  ();
-}
Index: packages/Python/lldbsuite/test/expression_command/completion-in-lambda-and-unnnamed-class/TestCompletionInLambdaAndUnnamedClass.py
===================================================================
--- /dev/null
+++ packages/Python/lldbsuite/test/expression_command/completion-in-lambda-and-unnnamed-class/TestCompletionInLambdaAndUnnamedClass.py
@@ -0,0 +1,4 @@
+from lldbsuite.test import lldbinline
+from lldbsuite.test import decorators
+
+lldbinline.MakeInlineTest(__file__, globals(),)
Index: packages/Python/lldbsuite/test/expression_command/completion-in-lambda-and-unnnamed-class/main.cpp
===================================================================
--- /dev/null
+++ packages/Python/lldbsuite/test/expression_command/completion-in-lambda-and-unnnamed-class/main.cpp
@@ -0,0 +1,11 @@
+int main() {
+  []()
+  { //%self.dbg.GetCommandInterpreter().HandleCompletion("e ", len("e "), 0, -1, lldb.SBStringList())
+  }
+  ();
+  struct {
+      void f()
+      { //%self.dbg.GetCommandInterpreter().HandleCompletion("e ", len("e "), 0, -1, lldb.SBStringList())
+      }
+  } A;
+}
Index: source/Symbol/ClangASTContext.cpp
===================================================================
--- source/Symbol/ClangASTContext.cpp
+++ source/Symbol/ClangASTContext.cpp
@@ -1502,14 +1502,44 @@
   // something is struct or a class, so we default to always use the more
   // complete definition just in case.
 
-  bool is_anonymous = (!name) || (!name[0]);
+  bool has_name = (!name) || (!name[0]);
 
   CXXRecordDecl *decl = CXXRecordDecl::Create(
       *ast, (TagDecl::TagKind)kind, decl_ctx, SourceLocation(),
-      SourceLocation(), is_anonymous ? nullptr : &ast->Idents.get(name));
+      SourceLocation(), has_name ? nullptr : &ast->Idents.get(name));
 
-  if (is_anonymous)
-    decl->setAnonymousStructOrUnion(true);
+  if (has_name) {
+    // In C++ a lambda is also represented as an unnamed class. This is
+    // different from an *anonymous class* that the user wrote:
+    //
+    // struct A {
+    //  // anonymous class
+    //  struct {
+    //    int x;
+    //  };
+    //  // unnamed class within a class
+    //  struct {
+    //    int y;
+    //  } B;
+    // };
+    //
+    // void f() {
+    //    // unammed class outside of a class
+    //    struct {
+    //      int z;
+    //    } C;
+    // }
+    //
+    // Anonymous classes is a GNU/MSVC extension that clang supports. It
+    // requires the anonymous class be embedded within a class. So the new
+    // heuristic verifies this condition.
+    //
+    // FIXME: An unnamed class within a class is also wrongly recognized as an
+    // anonymous struct.
+    if (CXXRecordDecl *record = dyn_cast<CXXRecordDecl>(decl_ctx)) {
+      decl->setAnonymousStructOrUnion(true);
+    }
+  }
 
   if (decl) {
     if (metadata)