diff --git a/interpreter/llvm/src/tools/clang/lib/Sema/SemaTemplateInstantiate.cpp b/interpreter/llvm/src/tools/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 3c76a05bcae93..8d48fe5789ee3 100644
--- a/interpreter/llvm/src/tools/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/interpreter/llvm/src/tools/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -2235,13 +2235,19 @@ Sema::InstantiateClass(SourceLocation PointOfInstantiation,
   // Exit the scope of this instantiation.
   SavedContext.pop();
 
-  Consumer.HandleTagDeclDefinition(Instantiation);
+  if (!Instantiation->isInvalidDecl()) {
+    // Always emit the vtable for an explicit instantiation definition
+    // of a polymorphic class template specialization. Otherwise, eagerly
+    // instantiate only constexpr virtual functions in preparation for their use
+    // in constant evaluation.
+    if (TSK == TSK_ExplicitInstantiationDefinition)
+      MarkVTableUsed(PointOfInstantiation, Instantiation, true);
+    else if (MightHaveConstexprVirtualFunctions)
+      MarkVirtualMembersReferenced(PointOfInstantiation, Instantiation,
+                                   /*ConstexprOnly*/ true);
+  }
 
-  // Always emit the vtable for an explicit instantiation definition
-  // of a polymorphic class template specialization.
-  if (!Instantiation->isInvalidDecl() &&
-      TSK == TSK_ExplicitInstantiationDefinition)
-    MarkVTableUsed(PointOfInstantiation, Instantiation, true);
+  Consumer.HandleTagDeclDefinition(Instantiation);
 
   return Instantiation->isInvalidDecl();
 }