diff --git a/clang/include/clang/Frontend/CompilerInvocation.h b/clang/include/clang/Frontend/CompilerInvocation.h
index 8fc51e6ec03b6..1a2a39411e58d 100644
--- a/clang/include/clang/Frontend/CompilerInvocation.h
+++ b/clang/include/clang/Frontend/CompilerInvocation.h
@@ -201,6 +201,8 @@ class CompilerInvocationBase {
   /// @}
 };
 
+class CowCompilerInvocation;
+
 /// Helper class for holding the data necessary to invoke the compiler.
 ///
 /// This class is designed to represent an abstract "invocation" of the
@@ -220,6 +222,9 @@ class CompilerInvocation : public CompilerInvocationBase {
   }
   ~CompilerInvocation() = default;
 
+  explicit CompilerInvocation(const CowCompilerInvocation &X);
+  CompilerInvocation &operator=(const CowCompilerInvocation &X);
+
   /// Const getters.
   /// @{
   // Note: These need to be pulled in manually. Otherwise, they get hidden by
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 9555dbf663d33..691f3b989b81e 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -191,6 +191,17 @@ CompilerInvocationBase::shallow_copy_assign(const CompilerInvocationBase &X) {
   return *this;
 }
 
+CompilerInvocation::CompilerInvocation(const CowCompilerInvocation &X)
+    : CompilerInvocationBase(EmptyConstructor{}) {
+  CompilerInvocationBase::deep_copy_assign(X);
+}
+
+CompilerInvocation &
+CompilerInvocation::operator=(const CowCompilerInvocation &X) {
+  CompilerInvocationBase::deep_copy_assign(X);
+  return *this;
+}
+
 namespace {
 template <typename T>
 T &ensureOwned(std::shared_ptr<T> &Storage) {