diff --git a/clang/unittests/Serialization/ModuleCacheTest.cpp b/clang/unittests/Serialization/ModuleCacheTest.cpp
--- a/clang/unittests/Serialization/ModuleCacheTest.cpp
+++ b/clang/unittests/Serialization/ModuleCacheTest.cpp
@@ -14,6 +14,7 @@
 #include "clang/Lex/HeaderSearch.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/VirtualFileSystem.h"
 #include "llvm/Support/raw_ostream.h"
 
 #include "gtest/gtest.h"
@@ -98,6 +99,7 @@
       CompilerInstance::createDiagnostics(new DiagnosticOptions());
   CreateInvocationOptions CIOpts;
   CIOpts.Diags = Diags;
+  CIOpts.VFS = llvm::vfs::createPhysicalFileSystem();
 
   // First run should pass with no errors
   const char *Args[] = {"clang",        "-fmodules",          "-Fframeworks",
diff --git a/clang/unittests/Serialization/NoCommentsTest.cpp b/clang/unittests/Serialization/NoCommentsTest.cpp
--- a/clang/unittests/Serialization/NoCommentsTest.cpp
+++ b/clang/unittests/Serialization/NoCommentsTest.cpp
@@ -89,9 +89,9 @@
   CIOpts.Diags = Diags;
 
   std::string CacheBMIPath = llvm::Twine(TestDir + "/Comments.pcm").str();
-  const char *Args[] = {
-      "clang++",       "-std=c++20",    "--precompile", "-working-directory",
-      TestDir.c_str(), "Comments.cppm", "-o",           CacheBMIPath.c_str()};
+  std::string CCPMPath = llvm::Twine(TestDir).concat("/Comments.cppm").str();
+  const char *Args[] = {"clang++",        "-std=c++20", "--precompile",
+                        CCPMPath.c_str(), "-o",         CacheBMIPath.c_str()};
   std::shared_ptr<CompilerInvocation> Invocation =
       createInvocation(Args, CIOpts);
   ASSERT_TRUE(Invocation);
diff --git a/clang/unittests/Serialization/VarDeclConstantInitTest.cpp b/clang/unittests/Serialization/VarDeclConstantInitTest.cpp
--- a/clang/unittests/Serialization/VarDeclConstantInitTest.cpp
+++ b/clang/unittests/Serialization/VarDeclConstantInitTest.cpp
@@ -94,6 +94,7 @@
       CompilerInstance::createDiagnostics(new DiagnosticOptions());
   CreateInvocationOptions CIOpts;
   CIOpts.Diags = Diags;
+  CIOpts.VFS = llvm::vfs::createPhysicalFileSystem();
 
   std::string CacheBMIPath = llvm::Twine(TestDir + "/Cached.pcm").str();
   const char *Args[] = {