diff --git a/tools/cgeist/Lib/clang-mlir.cc b/tools/cgeist/Lib/clang-mlir.cc
index 87be7612df01..c8bde52dc071 100644
--- a/tools/cgeist/Lib/clang-mlir.cc
+++ b/tools/cgeist/Lib/clang-mlir.cc
@@ -5893,6 +5893,12 @@ static bool parseMLIR(const char *Argv0, std::vector<std::string> filenames,
       new Driver(binary, llvm::sys::getDefaultTargetTriple(), Diags));
   mlirclang::ArgumentList Argv;
   Argv.push_back(binary);
+  // TODO we should probably preserve the order of these args - they matter in
+  // some cases as is with this one - it has to be before the input file
+  if (Lang != "") {
+    Argv.push_back("-x");
+    Argv.emplace_back(Lang);
+  }
   for (const auto &filename : filenames) {
     Argv.emplace_back(filename);
   }
diff --git a/tools/cgeist/driver.cc b/tools/cgeist/driver.cc
index 8d34965f38a9..5125d1e02149 100644
--- a/tools/cgeist/driver.cc
+++ b/tools/cgeist/driver.cc
@@ -213,6 +213,9 @@ static cl::opt<bool> EarlyVerifier("early-verifier", cl::init(false),
 
 static cl::opt<bool> Verbose("v", cl::init(false), cl::desc("Verbose"));
 
+static cl::opt<std::string> Lang("x", cl::init(""),
+                                 cl::desc("Treat input as language"));
+
 static cl::list<std::string> includeDirs("I", cl::desc("include search path"),
                                          cl::cat(toolOptions));