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
@@ -1660,6 +1660,13 @@
   let Documentation = [NoDebugDocs];
 }
 
+def ForceDebugIfRequiredType : InheritableAttr {
+  let Spellings = [Clang<"force_debug_if_required_type">];
+  let Subjects = SubjectList<[CXXRecord]>;
+  let Documentation = [Undocumented];
+  let SimpleHandler = 1;
+}
+
 def NoDuplicate : InheritableAttr {
   let Spellings = [Clang<"noduplicate">];
   let Subjects = SubjectList<[Function]>;
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
@@ -2399,6 +2399,10 @@
   if (!CXXDecl)
     return false;
 
+  // Don't omit definition if marked with attribute.
+  if (RD->hasAttr<ForceDebugIfRequiredTypeAttr>())
+    return false;
+
   // Only emit complete debug info for a dynamic class when its vtable is
   // emitted.  However, Microsoft debuggers don't resolve type information
   // across DLL boundaries, so skip this optimization if the class or any of its
diff --git a/clang/test/CodeGenCXX/force-debug-attribute.cpp b/clang/test/CodeGenCXX/force-debug-attribute.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGenCXX/force-debug-attribute.cpp
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -DSETATTR=0 -emit-llvm -std=c++14 -debug-info-kind=constructor %s -o - | FileCheck %s --check-prefix=DEBUG
+// RUN: %clang_cc1 -DSETATTR=1 -emit-llvm -std=c++14 -debug-info-kind=constructor %s -o - | FileCheck %s --check-prefix=WITHATTR
+
+#if SETATTR
+#define DEBUGASNEEDED __attribute__((force_debug_if_required_type))
+#else
+#define DEBUGASNEEDED
+#endif
+
+// Struct that isn't constructed, so its full type info should be omitted with
+// -debug-info-kind=constructor.
+struct DEBUGASNEEDED some_struct {
+  some_struct() {}
+};
+
+void func1(some_struct s) {}
+// void func2() { func1(); }
+// DEBUG:  !DICompositeType({{.*}}name: "some_struct"
+// DEBUG-SAME:              flags: {{.*}}DIFlagFwdDecl
+// WITHATTR: !DICompositeType({{.*}}name: "some_struct"
+// WITHATTR-NOT: DIFlagFwdDecl
+