diff --git a/flang/include/flang/Frontend/FrontendOptions.h b/flang/include/flang/Frontend/FrontendOptions.h
--- a/flang/include/flang/Frontend/FrontendOptions.h
+++ b/flang/include/flang/Frontend/FrontendOptions.h
@@ -115,12 +115,17 @@
 enum class Language : uint8_t {
   Unknown,
 
+  /// MLIR: we accept this so that we can run the optimizer on it, and compile
+  /// it to LLVM IR, assembly or object code.
+  MLIR,
+
   /// LLVM IR: we accept this so that we can run the optimizer on it,
   /// and compile it to assembly or object code.
   LLVM_IR,
 
   /// @{ Languages that the frontend can parse and compile.
   Fortran,
+  ///@}
 };
 
 // Source file layout
diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -270,6 +270,8 @@
     if (dashX.isUnknown())
       dashX = llvm::StringSwitch<InputKind>(xValue)
                   .Case("ir", Language::LLVM_IR)
+                  .Case("fir", Language::MLIR)
+                  .Case("mlir", Language::MLIR)
                   .Default(Language::Unknown);
 
     if (dashX.isUnknown())
diff --git a/flang/lib/Frontend/FrontendActions.cpp b/flang/lib/Frontend/FrontendActions.cpp
--- a/flang/lib/Frontend/FrontendActions.cpp
+++ b/flang/lib/Frontend/FrontendActions.cpp
@@ -34,6 +34,7 @@
 #include "mlir/IR/Dialect.h"
 #include "mlir/Pass/PassManager.h"
 #include "mlir/Target/LLVMIR/ModuleTranslation.h"
+#include "mlir/Parser/Parser.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/DiagnosticFrontend.h"
 #include "llvm/ADT/StringRef.h"
@@ -87,6 +88,30 @@
     return (nullptr != llvmModule);
   }
 
+  // Load the MLIR dialects required by Flang
+  mlir::DialectRegistry registry;
+  mlirCtx = std::make_unique<mlir::MLIRContext>(registry);
+  fir::support::registerNonCodegenDialects(registry);
+  fir::support::loadNonCodegenDialects(*mlirCtx);
+  fir::support::loadDialects(*mlirCtx);
+  fir::support::registerLLVMTranslation(*mlirCtx);
+
+  // If the input is an MLIR file, just parse it and return.
+  if (this->getCurrentInput().getKind().getLanguage() == Language::MLIR) {
+    llvm::SourceMgr sourceMgr;
+    llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> fileOrErr =
+        llvm::MemoryBuffer::getFileOrSTDIN(getCurrentInput().getFile());
+    sourceMgr.AddNewSourceBuffer(std::move(*fileOrErr), llvm::SMLoc());
+    mlir::OwningOpRef<mlir::ModuleOp> module =
+        mlir::parseSourceFile<mlir::ModuleOp>(sourceMgr, mlirCtx.get());
+
+    if (!module || mlir::failed(module->verifyInvariants()))
+      return false;
+
+    mlirModule = std::make_unique<mlir::ModuleOp>(module.release());
+    return true;
+  }
+
   // Otherwise, generate an MLIR module from the input Fortran source
   assert(getCurrentInput().getKind().getLanguage() == Language::Fortran &&
          "Invalid input type - expecting a Fortran file");
@@ -96,12 +121,6 @@
 
   CompilerInstance &ci = this->getInstance();
 
-  // Load the MLIR dialects required by Flang
-  mlir::DialectRegistry registry;
-  mlirCtx = std::make_unique<mlir::MLIRContext>(registry);
-  fir::support::registerNonCodegenDialects(registry);
-  fir::support::loadNonCodegenDialects(*mlirCtx);
-
   // Create a LoweringBridge
   const common::IntrinsicTypeDefaultKinds &defKinds =
       ci.getInvocation().getSemanticsContext().defaultKinds();
diff --git a/flang/lib/Frontend/FrontendOptions.cpp b/flang/lib/Frontend/FrontendOptions.cpp
--- a/flang/lib/Frontend/FrontendOptions.cpp
+++ b/flang/lib/Frontend/FrontendOptions.cpp
@@ -42,6 +42,8 @@
 
   if (extension == "bc" || extension == "ll")
     return Language::LLVM_IR;
+  if (extension == "fir" || extension == "mlir")
+    return Language::MLIR;
 
   return Language::Unknown;
 }
diff --git a/flang/test/Fir/addrof.fir b/flang/test/Fir/addrof.fir
--- a/flang/test/Fir/addrof.fir
+++ b/flang/test/Fir/addrof.fir
@@ -1,4 +1,5 @@
 // RUN: tco %s | FileCheck %s
+// RUN: %flang_fc1 -emit-llvm %s -o - | FileCheck %s
 
 // CHECK: @var_x = external global i32
 fir.global @var_x : !fir.int<4> {}
diff --git a/flang/test/Fir/alloc.fir b/flang/test/Fir/alloc.fir
--- a/flang/test/Fir/alloc.fir
+++ b/flang/test/Fir/alloc.fir
@@ -1,4 +1,5 @@
 // RUN: tco %s | FileCheck %s
+// RUN: %flang_fc1 -emit-llvm  %s -o - | FileCheck %s
 
 // UNSUPPORTED: system-windows
 
diff --git a/flang/test/Fir/arrayset.fir b/flang/test/Fir/arrayset.fir
--- a/flang/test/Fir/arrayset.fir
+++ b/flang/test/Fir/arrayset.fir
@@ -1,4 +1,5 @@
 // RUN: tco %s | FileCheck %s
+// RUN: %flang_fc1 -emit-llvm %s -o - | FileCheck %s
 
 // CHECK-LABEL: define void @x([10 x float]* %0)
 func.func @x(%arr : !fir.ref<!fir.array<10xf32>>) {
diff --git a/flang/test/Fir/boxchar.fir b/flang/test/Fir/boxchar.fir
--- a/flang/test/Fir/boxchar.fir
+++ b/flang/test/Fir/boxchar.fir
@@ -1,4 +1,5 @@
 // RUN: tco --target=x86_64-unknown-linux-gnu %s | FileCheck %s
+// RUN: %flang_fc1 -emit-llvm -triple x86_64-unknown-linux-gnu %s -o - | FileCheck %s
 
 // Test of building and passing boxchar.
 
diff --git a/flang/test/Fir/embox.fir b/flang/test/Fir/embox.fir
--- a/flang/test/Fir/embox.fir
+++ b/flang/test/Fir/embox.fir
@@ -1,4 +1,5 @@
 // RUN: tco %s | FileCheck %s
+// RUN: %flang_fc1 -mmlir -disable-external-name-interop  -emit-llvm %s -o -| FileCheck %s
 
 
 // CHECK-LABEL: define void @_QPtest_callee({ i32*, i64, i32, i8, i8, i8, i8, [1 x [3 x i64]] }* %0)
diff --git a/flang/test/Fir/global-initialization.fir b/flang/test/Fir/global-initialization.fir
--- a/flang/test/Fir/global-initialization.fir
+++ b/flang/test/Fir/global-initialization.fir
@@ -1,4 +1,4 @@
-// RUN: tco --fir-to-llvm-ir %s | FileCheck %s
+// RUN: fir-opt --fir-to-llvm-ir %s | FileCheck %s
 
 fir.global internal @_QEmask : !fir.array<32xi32> {
   %c0_i32 = arith.constant 1 : i32
diff --git a/flang/test/Fir/global.fir b/flang/test/Fir/global.fir
--- a/flang/test/Fir/global.fir
+++ b/flang/test/Fir/global.fir
@@ -1,4 +1,5 @@
 // RUN: tco %s | FileCheck %s
+// RUN: %flang_fc1 -emit-llvm  %s -o - | FileCheck %s
 
 // CHECK: @g_i0 = global i32 0
 fir.global @g_i0 : i32 {
diff --git a/flang/test/Fir/ignore-missing-type-descriptor.fir b/flang/test/Fir/ignore-missing-type-descriptor.fir
--- a/flang/test/Fir/ignore-missing-type-descriptor.fir
+++ b/flang/test/Fir/ignore-missing-type-descriptor.fir
@@ -3,6 +3,7 @@
 // having to care with providing an ABI compliant derived type descriptor object.
 // Missing derived type descriptor pointers are replaced by null pointers.
 // RUN: tco --ignore-missing-type-desc -o - %s | FileCheck %s
+// RUN: %flang_fc1 -emit-llvm  -mmlir --ignore-missing-type-desc -o - %s | FileCheck %s
 
 !some_freestyle_type = !fir.type<some_not_mangled_type{j:i32}>
 
diff --git a/flang/test/Fir/inline.fir b/flang/test/Fir/inline.fir
--- a/flang/test/Fir/inline.fir
+++ b/flang/test/Fir/inline.fir
@@ -1,4 +1,5 @@
 // RUN: tco --target=x86_64-unknown-linux-gnu --inline-all %s -o - | FileCheck %s
+// RUN: %flang_fc1 -triple x86_64-unknown-linux-gnu -mmlir --inline-all -emit-llvm %s -o - | FileCheck %s
 
 // CHECK-LABEL: @add
 func.func @add(%a : i32, %b : i32) -> i32 {
diff --git a/flang/test/Fir/optional.fir b/flang/test/Fir/optional.fir
--- a/flang/test/Fir/optional.fir
+++ b/flang/test/Fir/optional.fir
@@ -1,4 +1,5 @@
 // RUN: tco %s | FileCheck %s
+// RUN: %flang_fc1 -emit-llvm %s -o - | FileCheck %s
 
 // Test fir.is_present and fir.absent codegen
 
diff --git a/flang/test/Fir/peephole.fir b/flang/test/Fir/peephole.fir
--- a/flang/test/Fir/peephole.fir
+++ b/flang/test/Fir/peephole.fir
@@ -1,4 +1,5 @@
 // RUN: tco %s | FileCheck %s
+// RUN: %flang_fc1 -emit-llvm %s -o - | FileCheck %s
 
 // Test peephole optimizations
 
diff --git a/flang/test/Fir/rebox-susbtring.fir b/flang/test/Fir/rebox-susbtring.fir
--- a/flang/test/Fir/rebox-susbtring.fir
+++ b/flang/test/Fir/rebox-susbtring.fir
@@ -1,6 +1,6 @@
 // Test translation to llvm IR of fir.rebox with substring array sections.
 
-// RUN: tco -o - -cg-rewrite --fir-to-llvm-ir -cse %s | FileCheck %s
+// RUN: fir-opt -o - -cg-rewrite --fir-to-llvm-ir -cse %s | FileCheck %s
 
 // Test a fir.rebox with a substring on a character array with constant
 // length (like c(:)(2:*) where c is a fir.box array with constant length).
diff --git a/flang/test/Fir/rebox.fir b/flang/test/Fir/rebox.fir
--- a/flang/test/Fir/rebox.fir
+++ b/flang/test/Fir/rebox.fir
@@ -1,4 +1,5 @@
 // RUN: tco %s | FileCheck %s
+// RUN: %flang_fc1 -emit-llvm %s -o - | FileCheck %s
 
 // Test applying slice on fir.box
 //   subroutine foo(x)
diff --git a/flang/test/Fir/select.fir b/flang/test/Fir/select.fir
--- a/flang/test/Fir/select.fir
+++ b/flang/test/Fir/select.fir
@@ -1,6 +1,7 @@
 // Test lowering FIR to LLVM IR of fir.select{|_rank|_case}
 
 // RUN: tco %s | FileCheck %s
+// RUN: %flang_fc1 -emit-llvm %s -o - | FileCheck %s
 
 // CHECK-LABEL: @f
 func.func @f(%a : i32) -> i32 {
diff --git a/flang/test/Fir/widechar.fir b/flang/test/Fir/widechar.fir
--- a/flang/test/Fir/widechar.fir
+++ b/flang/test/Fir/widechar.fir
@@ -1,4 +1,5 @@
 // RUN: tco %s | FileCheck %s
+// RUN: %flang_fc1 -emit-llvm %s -o - | FileCheck %s
 
 // CHECK-LABEL: @character_literal1
 func.func @character_literal1() -> !fir.char<1,13> {
diff --git a/flang/test/Lower/common-block.f90 b/flang/test/Lower/common-block.f90
--- a/flang/test/Lower/common-block.f90
+++ b/flang/test/Lower/common-block.f90
@@ -1,4 +1,5 @@
 ! RUN: bbc %s -o - | tco | FileCheck %s
+! RUN: %flang -emit-llvm -S -mmlir -disable-external-name-interop %s -o - | FileCheck %s
 
 ! CHECK: @_QB = common global [8 x i8] zeroinitializer
 ! CHECK: @_QBrien = common global [1 x i8] zeroinitializer
diff --git a/flang/test/Lower/complex-part.f90 b/flang/test/Lower/complex-part.f90
--- a/flang/test/Lower/complex-part.f90
+++ b/flang/test/Lower/complex-part.f90
@@ -1,4 +1,5 @@
 ! RUN: bbc %s -o - | tco | FileCheck %s
+! RUN: %flang -emit-llvm -S -mmlir -disable-external-name-interop %s -o - | FileCheck %s
 
   COMPLEX c
   c%RE = 3.14
diff --git a/flang/test/Lower/forall/character-1.f90 b/flang/test/Lower/forall/character-1.f90
--- a/flang/test/Lower/forall/character-1.f90
+++ b/flang/test/Lower/forall/character-1.f90
@@ -1,4 +1,5 @@
 ! RUN: bbc %s -o - | tco | FileCheck %s
+! RUN: %flang -emit-llvm -S -mmlir -disable-external-name-interop %s -o - | FileCheck %s
 ! Test from Fortran source through to LLVM IR.
 ! UNSUPPORTED: system-windows
 
@@ -23,7 +24,7 @@
 ! CHECK: %[[elesize:.*]] = getelementptr { {{.*}}, [1 x [3 x i64]] }, { {{.*}}, [1 x [3 x i64]] }* %[[arg]], i32 0, i32 1
 ! CHECK: %[[esval:.*]] = load i64, i64* %[[elesize]]
 ! CHECK: %[[mul:.*]] = mul i64 1, %[[esval]]
-! CHECK: %[[mul2:.*]] = mul i64 %[[mul]], %[[extval]], !dbg !18
+! CHECK: %[[mul2:.*]] = mul i64 %[[mul]], %[[extval]]
 ! CHECK: %[[buff:.*]] = call i8* @malloc(i64 %[[mul2]])
 ! CHECK: %[[to:.*]] = getelementptr i8, i8* %[[buff]], i64 %
 ! CHECK: call void @llvm.memmove.p0i8.p0i8.i64(i8* %[[to]], i8* %{{.*}}, i64 %{{.*}}, i1 false)