diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -1673,6 +1673,14 @@
   let Documentation = [NoDebugDocs];
 }
 
+def StandaloneDebug : InheritableAttr {
+  let Spellings = [Clang<"standalone_debug", /*allowInC =*/0>];
+  let Subjects = SubjectList<[CXXRecord]>;
+  let Documentation = [StandaloneDebugDocs];
+  let SimpleHandler = 1;
+  let LangOpts = [CPlusPlus];
+}
+
 def NoDuplicate : InheritableAttr {
   let Spellings = [Clang<"noduplicate">];
   let Subjects = SubjectList<[Function]>;
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -1102,6 +1102,16 @@
   }];
 }
 
+def StandaloneDebugDocs : Documentation {
+  let Category = DocCatVariable;
+  let Content = [{
+The ``standalone_debug`` attribute causes debug info to be emitted for a record
+type regardless of the debug info optimizations that are enabled with
+-fno-standalone-debug. This attribute only has an effect when debug info
+optimizations are enabled (e.g. with -fno-standalone-debug), and is C++-only.
+  }];
+}
+
 def NoDuplicateDocs : Documentation {
   let Category = DocCatFunction;
   let Content = [{
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -2385,7 +2385,8 @@
   if (DebugKind == codegenoptions::DebugLineTablesOnly)
     return true;
 
-  if (DebugKind > codegenoptions::LimitedDebugInfo)
+  if (DebugKind > codegenoptions::LimitedDebugInfo ||
+      RD->hasAttr<StandaloneDebugAttr>())
     return false;
 
   if (!LangOpts.CPlusPlus)
diff --git a/clang/test/CodeGenCXX/standalone-debug-attribute.cpp b/clang/test/CodeGenCXX/standalone-debug-attribute.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGenCXX/standalone-debug-attribute.cpp
@@ -0,0 +1,54 @@
+// RUN: %clang_cc1 -DSETATTR=0 -triple x86_64-unknown-linux-gnu -emit-llvm -debug-info-kind=constructor %s -o - | FileCheck %s --check-prefix=DEBUG
+// RUN: %clang_cc1 -DSETATTR=1 -triple x86_64-unknown-linux-gnu -emit-llvm -debug-info-kind=constructor %s -o - | FileCheck %s --check-prefix=WITHATTR
+// Use -debug-info-kind=constructor because it includes all the optimizations.
+
+#if SETATTR
+#define STANDALONEDEBUGATTR __attribute__((standalone_debug))
+#else
+#define STANDALONEDEBUGATTR
+#endif
+
+struct STANDALONEDEBUGATTR StructWithConstructor {
+  StructWithConstructor() {}
+};
+void f(StructWithConstructor s) {}
+// DEBUG:  !DICompositeType({{.*}}name: "StructWithConstructor"
+// DEBUG-SAME:              flags: {{.*}}DIFlagFwdDecl
+// WITHATTR: !DICompositeType({{.*}}name: "StructWithConstructor"
+// WITHATTR-NOT: DIFlagFwdDecl
+
+union STANDALONEDEBUGATTR UnionWithConstructor {
+  UnionWithConstructor() {}
+};
+void f(UnionWithConstructor u) {}
+// DEBUG:  !DICompositeType({{.*}}name: "UnionWithConstructor"
+// DEBUG-SAME:              flags: {{.*}}DIFlagFwdDecl
+// WITHATTR: !DICompositeType({{.*}}name: "UnionWithConstructor"
+// WITHATTR-NOT: DIFlagFwdDecl
+
+template <typename T> struct ExternTemplate {
+  ExternTemplate() {}
+  T x;
+};
+extern template struct STANDALONEDEBUGATTR ExternTemplate<int>;
+void f(ExternTemplate<int> s) {}
+// DEBUG: !DICompositeType({{.*}}name: "ExternTemplate<int>"
+// DEBUG-SAME:             flags: {{.*}}DIFlagFwdDecl
+// WITHATTR: !DICompositeType({{.*}}name: "ExternTemplate<int>"
+// WITHATTR-NOT: DIFlagFwdDecl
+
+struct STANDALONEDEBUGATTR CompleteTypeRequired {};
+void f(CompleteTypeRequired &s) {}
+// DEBUG: !DICompositeType({{.*}}name: "CompleteTypeRequired"
+// DEBUG-SAME:             flags: {{.*}}DIFlagFwdDecl
+// WITHATTR: !DICompositeType({{.*}}name: "CompleteTypeRequired"
+// WITHATTR-NOT: DIFlagFwdDecl
+
+struct STANDALONEDEBUGATTR Redecl;
+struct Redecl {};
+void f(Redecl &s) {}
+// DEBUG: !DICompositeType({{.*}}name: "Redecl"
+// DEBUG-SAME:             flags: {{.*}}DIFlagFwdDecl
+// WITHATTR: !DICompositeType({{.*}}name: "Redecl"
+// WITHATTR-NOT: DIFlagFwdDecl
+
diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
--- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -154,6 +154,7 @@
 // CHECK-NEXT: Section (SubjectMatchRule_function, SubjectMatchRule_variable_is_global, SubjectMatchRule_objc_method, SubjectMatchRule_objc_property)
 // CHECK-NEXT: SetTypestate (SubjectMatchRule_function_is_member)
 // CHECK-NEXT: SpeculativeLoadHardening (SubjectMatchRule_function, SubjectMatchRule_objc_method)
+// CHECK-NEXT: StandaloneDebug (SubjectMatchRule_record)
 // CHECK-NEXT: SwiftAsync (SubjectMatchRule_function, SubjectMatchRule_objc_method)
 // CHECK-NEXT: SwiftAsyncError (SubjectMatchRule_function, SubjectMatchRule_objc_method)
 // CHECK-NEXT: SwiftAsyncName (SubjectMatchRule_objc_method, SubjectMatchRule_function)
diff --git a/clang/test/Sema/attr-standalonedebug.cpp b/clang/test/Sema/attr-standalonedebug.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/Sema/attr-standalonedebug.cpp
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 %s -verify -fsyntax-only
+// RUN: %clang_cc1 %s -verify -fsyntax-only -x c
+
+#ifdef __cplusplus
+int a __attribute__((standalone_debug)); // expected-warning {{'standalone_debug' attribute only applies to classes}}
+
+void __attribute__((standalone_debug)) b(); // expected-warning {{'standalone_debug' attribute only applies to classes}}
+
+struct __attribute__((standalone_debug(1))) c {}; // expected-error {{'standalone_debug' attribute takes no arguments}}
+
+#else
+// Check that attribute only works in C++.
+struct __attribute__((standalone_debug)) a {}; // expected-warning {{'standalone_debug' attribute ignored}}
+#endif