diff --git a/include/swift/Frontend/Frontend.h b/include/swift/Frontend/Frontend.h
index bdfa5fa2c9c13..4ea8e4c963a40 100644
--- a/include/swift/Frontend/Frontend.h
+++ b/include/swift/Frontend/Frontend.h
@@ -188,6 +188,10 @@ class CompilerInvocation {
     return SearchPathOpts.getFrameworkSearchPaths();
   }
 
+  void setVFSOverlays(const std::vector<std::string> &Overlays) {
+    SearchPathOpts.VFSOverlayFiles = Overlays;
+  }
+
   void setCompilerPluginLibraryPaths(const std::vector<std::string> &Paths) {
     SearchPathOpts.setCompilerPluginLibraryPaths(Paths);
   }
diff --git a/tools/sil-opt/SILOpt.cpp b/tools/sil-opt/SILOpt.cpp
index 1142346c22600..c7dabc6075b82 100644
--- a/tools/sil-opt/SILOpt.cpp
+++ b/tools/sil-opt/SILOpt.cpp
@@ -86,6 +86,9 @@ ImportPaths("I", llvm::cl::desc("add a directory to the import search path"));
 static llvm::cl::list<std::string>
 FrameworkPaths("F", llvm::cl::desc("add a directory to the framework search path"));
 
+static llvm::cl::list<std::string>
+VFSOverlays("vfsoverlay", llvm::cl::desc("add a VFS overlay"));
+
 static llvm::cl::opt<std::string>
 ModuleName("module-name", llvm::cl::desc("The name of the module if processing"
                                          " a module. Necessary for processing "
@@ -542,6 +545,9 @@ int main(int argc, char **argv) {
     FramePaths.push_back({path, /*isSystem=*/false});
   }
   Invocation.setFrameworkSearchPaths(FramePaths);
+
+  Invocation.setVFSOverlays(VFSOverlays);
+
   // Set the SDK path and target if given.
   if (SDKPath.getNumOccurrences() == 0) {
     const char *SDKROOT = getenv("SDKROOT");