diff --git a/lib/Serialization/Serialization.cpp b/lib/Serialization/Serialization.cpp
index a9916f44b0442..867b399308528 100644
--- a/lib/Serialization/Serialization.cpp
+++ b/lib/Serialization/Serialization.cpp
@@ -738,8 +738,24 @@ void Serializer::writeHeader(const SerializationOptions &options) {
         options_block::XCCLayout XCC(Out);
 
         SDKPath.emit(ScratchRecord, M->getASTContext().SearchPathOpts.SDKPath);
-        for (const std::string &arg : options.ExtraClangOptions) {
-          XCC.emit(ScratchRecord, arg);
+        auto &Opts = options.ExtraClangOptions;
+        for (auto Arg = Opts.begin(), E = Opts.end(); Arg != E; ++Arg) { 
+          // FIXME: This is a hack and calls for a better design.
+          //
+          // Filter out any -ivfsoverlay options that include an
+          // unextended-module-overlay.yaml overlay. By convention the Xcode
+          // buildsystem uses these while *building* mixed Objective-C and Swift
+          // frameworks; but they should never be used to *import* the module
+          // defined in the framework.
+          if (StringRef(*Arg).startswith("-ivfsoverlay")) {
+            auto Next = std::next(Arg);
+            if (Next != E &&
+                StringRef(*Next).endswith("unextended-module-overlay.yaml")) {
+              ++Arg;
+              continue;
+            }
+          }
+          XCC.emit(ScratchRecord, *Arg);
         }
       }
     }
diff --git a/test/Inputs/unextended-module-overlay.yaml b/test/Inputs/unextended-module-overlay.yaml
new file mode 100644
index 0000000000000..e3428038165bb
--- /dev/null
+++ b/test/Inputs/unextended-module-overlay.yaml
@@ -0,0 +1,4 @@
+{
+  'version': 0,
+  'roots': []
+}
diff --git a/test/Serialization/search-paths-relative.swift b/test/Serialization/search-paths-relative.swift
index a9987705a5c14..fe1b26310bd3f 100644
--- a/test/Serialization/search-paths-relative.swift
+++ b/test/Serialization/search-paths-relative.swift
@@ -3,7 +3,7 @@
 // RUN: mkdir -p %t/Frameworks/has_alias.framework/Modules/has_alias.swiftmodule/
 // RUN: %target-swift-frontend -emit-module -o %t/Frameworks/has_alias.framework/Modules/has_alias.swiftmodule/%target-swiftmodule-name %S/Inputs/alias.swift -module-name has_alias
 
-// RUN: cd %t/secret && %target-swiftc_driver -emit-module -o %t/has_xref.swiftmodule -I . -F ../Frameworks -parse-as-library %S/Inputs/has_xref.swift %S/../Inputs/empty.swift -Xfrontend -serialize-debugging-options -Xcc -DDUMMY
+// RUN: cd %t/secret && %target-swiftc_driver -emit-module -o %t/has_xref.swiftmodule -I . -F ../Frameworks -parse-as-library %S/Inputs/has_xref.swift %S/../Inputs/empty.swift -Xfrontend -serialize-debugging-options -Xcc -ivfsoverlay -Xcc %S/../Inputs/unextended-module-overlay.yaml -Xcc -DDUMMY
 // RUN: %target-swift-frontend %s -typecheck -I %t
 
 // Check the actual serialized search paths.
@@ -30,3 +30,5 @@ numeric(42)
 
 // NEGATIVE-NOT: '.'
 // NEGATIVE-NOT: '../Frameworks'
+// This should be filtered out.
+// NEGATIVE-NOT: -ivfsoverlay{{.*}}unextended-module-overlay.yaml