diff --git a/clang/include/clang/Frontend/CompilerInvocation.h b/clang/include/clang/Frontend/CompilerInvocation.h
--- a/clang/include/clang/Frontend/CompilerInvocation.h
+++ b/clang/include/clang/Frontend/CompilerInvocation.h
@@ -91,8 +91,9 @@
 
   CompilerInvocationRefBase();
   CompilerInvocationRefBase(const CompilerInvocationRefBase &X);
-  CompilerInvocationRefBase &
-  operator=(const CompilerInvocationRefBase &) = delete;
+  CompilerInvocationRefBase(CompilerInvocationRefBase &&X);
+  CompilerInvocationRefBase &operator=(CompilerInvocationRefBase X);
+  CompilerInvocationRefBase &operator=(CompilerInvocationRefBase &&X);
   ~CompilerInvocationRefBase();
 
   LangOptions *getLangOpts() { return LangOpts.get(); }
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -125,6 +125,23 @@
       PreprocessorOpts(new PreprocessorOptions(X.getPreprocessorOpts())),
       AnalyzerOpts(new AnalyzerOptions(*X.getAnalyzerOpts())) {}
 
+CompilerInvocationRefBase::CompilerInvocationRefBase(
+    CompilerInvocationRefBase &&X) = default;
+
+CompilerInvocationRefBase &
+CompilerInvocationRefBase::operator=(CompilerInvocationRefBase X) {
+  LangOpts.swap(X.LangOpts);
+  TargetOpts.swap(X.TargetOpts);
+  DiagnosticOpts.swap(X.DiagnosticOpts);
+  HeaderSearchOpts.swap(X.HeaderSearchOpts);
+  PreprocessorOpts.swap(X.PreprocessorOpts);
+  AnalyzerOpts.swap(X.AnalyzerOpts);
+  return *this;
+}
+
+CompilerInvocationRefBase &
+CompilerInvocationRefBase::operator=(CompilerInvocationRefBase &&X) = default;
+
 CompilerInvocationRefBase::~CompilerInvocationRefBase() = default;
 
 //===----------------------------------------------------------------------===//
diff --git a/clang/unittests/Frontend/CompilerInvocationTest.cpp b/clang/unittests/Frontend/CompilerInvocationTest.cpp
--- a/clang/unittests/Frontend/CompilerInvocationTest.cpp
+++ b/clang/unittests/Frontend/CompilerInvocationTest.cpp
@@ -97,7 +97,7 @@
   ASSERT_THAT(Array, ContainsN(StrEq("x"), 2));
 }
 
-// Copy constructor performs a deep copy of reference-counted pointers.
+// Copy constructor/assignment perform deep copy of reference-counted pointers.
 
 TEST(CompilerInvocationTest, DeepCopyConstructor) {
   CompilerInvocation A;
@@ -109,6 +109,17 @@
   ASSERT_EQ(A.getAnalyzerOpts()->Config["Key"], "Old");
 }
 
+TEST(CompilerInvocationTest, DeepCopyAssignment) {
+  CompilerInvocation A;
+  A.getAnalyzerOpts()->Config["Key"] = "Old";
+
+  CompilerInvocation B;
+  B = A;
+  B.getAnalyzerOpts()->Config["Key"] = "New";
+
+  ASSERT_EQ(A.getAnalyzerOpts()->Config["Key"], "Old");
+}
+
 // Boolean option with a keypath that defaults to true.
 // The only flag with a negative spelling can set the keypath to false.