diff --git a/mlir/test/lib/Dialect/Test/TestDialect.h b/mlir/test/lib/Dialect/Test/TestDialect.h
--- a/mlir/test/lib/Dialect/Test/TestDialect.h
+++ b/mlir/test/lib/Dialect/Test/TestDialect.h
@@ -38,7 +38,9 @@
 #include "TestOps.h.inc"
 
 namespace mlir {
+namespace test {
 void registerTestDialect(DialectRegistry &registry);
-} // end namespace mlir
+} // namespace test
+} // namespace mlir
 
 #endif // MLIR_TESTDIALECT_H
diff --git a/mlir/test/lib/Dialect/Test/TestDialect.cpp b/mlir/test/lib/Dialect/Test/TestDialect.cpp
--- a/mlir/test/lib/Dialect/Test/TestDialect.cpp
+++ b/mlir/test/lib/Dialect/Test/TestDialect.cpp
@@ -20,8 +20,9 @@
 #include "llvm/ADT/StringSwitch.h"
 
 using namespace mlir;
+using namespace mlir::test;
 
-void mlir::registerTestDialect(DialectRegistry &registry) {
+void mlir::test::registerTestDialect(DialectRegistry &registry) {
   registry.insert<TestDialect>();
 }
 
diff --git a/mlir/test/lib/Dialect/Test/TestOps.td b/mlir/test/lib/Dialect/Test/TestOps.td
--- a/mlir/test/lib/Dialect/Test/TestOps.td
+++ b/mlir/test/lib/Dialect/Test/TestOps.td
@@ -21,7 +21,7 @@
 
 def Test_Dialect : Dialect {
   let name = "test";
-  let cppNamespace = "::mlir";
+  let cppNamespace = "::mlir::test";
   let hasOperationAttrVerify = 1;
   let hasRegionArgAttrVerify = 1;
   let hasRegionResultAttrVerify = 1;
@@ -89,8 +89,8 @@
 }
 
 def TEST_TestType : DialectType<Test_Dialect,
-    CPred<"$_self.isa<::mlir::TestType>()">, "test">,
-    BuildableType<"$_builder.getType<::mlir::TestType>()">;
+    CPred<"$_self.isa<::mlir::test::TestType>()">, "test">,
+    BuildableType<"$_builder.getType<::mlir::test::TestType>()">;
 
 //===----------------------------------------------------------------------===//
 // Test Symbols
diff --git a/mlir/test/lib/Dialect/Test/TestPatterns.cpp b/mlir/test/lib/Dialect/Test/TestPatterns.cpp
--- a/mlir/test/lib/Dialect/Test/TestPatterns.cpp
+++ b/mlir/test/lib/Dialect/Test/TestPatterns.cpp
@@ -16,6 +16,7 @@
 #include "mlir/Transforms/GreedyPatternRewriteDriver.h"
 
 using namespace mlir;
+using namespace mlir::test;
 
 // Native function for testing NativeCodeCall
 static Value chooseOperand(Value input1, Value input2, BoolAttr choice) {
@@ -955,6 +956,7 @@
 //===----------------------------------------------------------------------===//
 
 namespace mlir {
+namespace test {
 void registerPatternsTestPass() {
   PassRegistration<TestReturnTypeDriver>("test-return-type",
                                          "Run return type functions");
@@ -987,4 +989,5 @@
       "test-merge-blocks",
       "Test Merging operation in ConversionPatternRewriter"};
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Dialect/Test/TestTraits.cpp b/mlir/test/lib/Dialect/Test/TestTraits.cpp
--- a/mlir/test/lib/Dialect/Test/TestTraits.cpp
+++ b/mlir/test/lib/Dialect/Test/TestTraits.cpp
@@ -11,6 +11,7 @@
 #include "mlir/Transforms/GreedyPatternRewriteDriver.h"
 
 using namespace mlir;
+using namespace mlir::test;
 
 //===----------------------------------------------------------------------===//
 // Trait Folder.
diff --git a/mlir/test/lib/Dialect/Test/TestTypeDefs.td b/mlir/test/lib/Dialect/Test/TestTypeDefs.td
--- a/mlir/test/lib/Dialect/Test/TestTypeDefs.td
+++ b/mlir/test/lib/Dialect/Test/TestTypeDefs.td
@@ -55,7 +55,7 @@
   let parameters = (
     ins
     // SignednessSemantics is defined below.
-    "::mlir::TestIntegerType::SignednessSemantics":$signedness,
+    "::mlir::test::TestIntegerType::SignednessSemantics":$signedness,
     "unsigned":$width
   );
 
@@ -108,7 +108,7 @@
     // An ArrayRef of something which requires allocation in the storage
     // constructor.
     ArrayRefOfSelfAllocationParameter<
-      "::mlir::FieldInfo", // FieldInfo is defined/declared in TestTypes.h.
+      "::mlir::test::FieldInfo", // FieldInfo is defined/declared in TestTypes.h.
       "Models struct fields">: $fields
   );
 
diff --git a/mlir/test/lib/Dialect/Test/TestTypes.h b/mlir/test/lib/Dialect/Test/TestTypes.h
--- a/mlir/test/lib/Dialect/Test/TestTypes.h
+++ b/mlir/test/lib/Dialect/Test/TestTypes.h
@@ -23,6 +23,7 @@
 #include "mlir/IR/Types.h"
 
 namespace mlir {
+namespace test {
 
 /// FieldInfo represents a field in the StructType data type. It is used as a
 /// parameter in TestTypeDefs.td.
@@ -36,12 +37,14 @@
   }
 };
 
+} // namespace test
 } // namespace mlir
 
 #define GET_TYPEDEF_CLASSES
 #include "TestTypeDefs.h.inc"
 
 namespace mlir {
+namespace test {
 
 #include "TestTypeInterfaces.h.inc"
 
@@ -104,6 +107,7 @@
   StringRef getName() { return getImpl()->name; }
 };
 
-} // end namespace mlir
+} // namespace test
+} // namespace mlir
 
 #endif // MLIR_TESTTYPES_H
diff --git a/mlir/test/lib/Dialect/Test/TestTypes.cpp b/mlir/test/lib/Dialect/Test/TestTypes.cpp
--- a/mlir/test/lib/Dialect/Test/TestTypes.cpp
+++ b/mlir/test/lib/Dialect/Test/TestTypes.cpp
@@ -18,6 +18,7 @@
 #include "llvm/ADT/TypeSwitch.h"
 
 using namespace mlir;
+using namespace mlir::test;
 
 // Custom parser for SignednessSemantics.
 static ParseResult
@@ -87,21 +88,23 @@
 // namespace. Declare them here, then define them immediately below. Separating
 // the declaration and definition adheres to the LLVM coding standards.
 namespace mlir {
+namespace test {
 // FieldInfo is used as part of a parameter, so equality comparison is
 // compulsory.
 static bool operator==(const FieldInfo &a, const FieldInfo &b);
 // FieldInfo is used as part of a parameter, so a hash will be computed.
 static llvm::hash_code hash_value(const FieldInfo &fi); // NOLINT
+} // namespace test
 } // namespace mlir
 
 // FieldInfo is used as part of a parameter, so equality comparison is
 // compulsory.
-static bool mlir::operator==(const FieldInfo &a, const FieldInfo &b) {
+static bool mlir::test::operator==(const FieldInfo &a, const FieldInfo &b) {
   return a.name == b.name && a.type == b.type;
 }
 
 // FieldInfo is used as part of a parameter, so a hash will be computed.
-static llvm::hash_code mlir::hash_value(const FieldInfo &fi) { // NOLINT
+static llvm::hash_code mlir::test::hash_value(const FieldInfo &fi) { // NOLINT
   return llvm::hash_combine(fi.name, fi.type);
 }
 
diff --git a/mlir/test/lib/IR/TestInterfaces.cpp b/mlir/test/lib/IR/TestInterfaces.cpp
--- a/mlir/test/lib/IR/TestInterfaces.cpp
+++ b/mlir/test/lib/IR/TestInterfaces.cpp
@@ -10,6 +10,7 @@
 #include "mlir/Pass/Pass.h"
 
 using namespace mlir;
+using namespace mlir::test;
 
 namespace {
 /// This test checks various aspects of Type interface generation and
@@ -34,8 +35,10 @@
 } // end anonymous namespace
 
 namespace mlir {
+namespace test {
 void registerTestInterfaces() {
   PassRegistration<TestTypeInterfaces> pass("test-type-interfaces",
                                             "Test type interface support.");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/IR/TestTypes.cpp b/mlir/test/lib/IR/TestTypes.cpp
--- a/mlir/test/lib/IR/TestTypes.cpp
+++ b/mlir/test/lib/IR/TestTypes.cpp
@@ -11,6 +11,7 @@
 #include "mlir/Pass/Pass.h"
 
 using namespace mlir;
+using namespace mlir::test;
 
 namespace {
 struct TestRecursiveTypesPass
@@ -36,7 +37,7 @@
     signalPassFailure();
   }
 };
-} // end namespace
+} // namespace
 
 LogicalResult TestRecursiveTypesPass::createIRWithTypes() {
   MLIRContext *ctx = &getContext();
@@ -69,10 +70,12 @@
 }
 
 namespace mlir {
+namespace test {
 
 void registerTestRecursiveTypesPass() {
   PassRegistration<TestRecursiveTypesPass> reg(
       "test-recursive-types", "Test support for recursive types");
 }
 
-} // end namespace mlir
+} // namespace test
+} // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestAffineLoopParametricTiling.cpp b/mlir/test/lib/Transforms/TestAffineLoopParametricTiling.cpp
--- a/mlir/test/lib/Transforms/TestAffineLoopParametricTiling.cpp
+++ b/mlir/test/lib/Transforms/TestAffineLoopParametricTiling.cpp
@@ -20,7 +20,6 @@
 #define DEBUG_TYPE "test-affine-parametric-tile"
 
 namespace {
-
 struct TestAffineLoopParametricTiling
     : public PassWrapper<TestAffineLoopParametricTiling, FunctionPass> {
   void runOnFunction() override;
@@ -82,9 +81,11 @@
 }
 
 namespace mlir {
+namespace test {
 void registerTestAffineLoopParametricTilingPass() {
   PassRegistration<TestAffineLoopParametricTiling>(
       "test-affine-parametric-tile",
       "Tile affine loops using SSA values as tile sizes");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestCallGraph.cpp b/mlir/test/lib/Transforms/TestCallGraph.cpp
--- a/mlir/test/lib/Transforms/TestCallGraph.cpp
+++ b/mlir/test/lib/Transforms/TestCallGraph.cpp
@@ -27,8 +27,10 @@
 } // end anonymous namespace
 
 namespace mlir {
+namespace test {
 void registerTestCallGraphPass() {
   PassRegistration<TestCallGraphPass> pass(
       "test-print-callgraph", "Print the contents of a constructed callgraph.");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestConstantFold.cpp b/mlir/test/lib/Transforms/TestConstantFold.cpp
--- a/mlir/test/lib/Transforms/TestConstantFold.cpp
+++ b/mlir/test/lib/Transforms/TestConstantFold.cpp
@@ -65,8 +65,10 @@
 }
 
 namespace mlir {
+namespace test {
 void registerTestConstantFold() {
   PassRegistration<TestConstantFold>("test-constant-fold",
                                      "Test operation constant folding");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestConvVectorization.cpp b/mlir/test/lib/Transforms/TestConvVectorization.cpp
--- a/mlir/test/lib/Transforms/TestConvVectorization.cpp
+++ b/mlir/test/lib/Transforms/TestConvVectorization.cpp
@@ -124,8 +124,10 @@
 }
 
 namespace mlir {
+namespace test {
 void registerTestConvVectorization() {
   PassRegistration<TestConvVectorization> testTransformPatternsPass(
       "test-conv-vectorization", "Test vectorization of convolutions");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestConvertCallOp.cpp b/mlir/test/lib/Transforms/TestConvertCallOp.cpp
--- a/mlir/test/lib/Transforms/TestConvertCallOp.cpp
+++ b/mlir/test/lib/Transforms/TestConvertCallOp.cpp
@@ -19,9 +19,10 @@
 namespace {
 
 class TestTypeProducerOpConverter
-    : public ConvertOpToLLVMPattern<TestTypeProducerOp> {
+    : public ConvertOpToLLVMPattern<test::TestTypeProducerOp> {
 public:
-  using ConvertOpToLLVMPattern<TestTypeProducerOp>::ConvertOpToLLVMPattern;
+  using ConvertOpToLLVMPattern<
+      test::TestTypeProducerOp>::ConvertOpToLLVMPattern;
 
   LogicalResult
   matchAndRewrite(Operation *op, ArrayRef<Value> operands,
@@ -43,7 +44,7 @@
 
     // Populate type conversions.
     LLVMTypeConverter type_converter(m.getContext());
-    type_converter.addConversion([&](TestType type) {
+    type_converter.addConversion([&](test::TestType type) {
       return LLVM::LLVMType::getInt8PtrTy(m.getContext());
     });
 
@@ -55,7 +56,7 @@
     // Set target.
     ConversionTarget target(getContext());
     target.addLegalDialect<LLVM::LLVMDialect>();
-    target.addIllegalDialect<TestDialect>();
+    target.addIllegalDialect<test::TestDialect>();
     target.addIllegalDialect<StandardOpsDialect>();
 
     if (failed(applyPartialConversion(m, target, std::move(patterns))))
@@ -66,10 +67,12 @@
 } // namespace
 
 namespace mlir {
+namespace test {
 void registerConvertCallOpPass() {
   PassRegistration<TestConvertCallOp>(
       "test-convert-call-op",
       "Tests conversion of `std.call` to `llvm.call` in "
       "presence of custom types");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestConvertGPUKernelToCubin.cpp b/mlir/test/lib/Transforms/TestConvertGPUKernelToCubin.cpp
--- a/mlir/test/lib/Transforms/TestConvertGPUKernelToCubin.cpp
+++ b/mlir/test/lib/Transforms/TestConvertGPUKernelToCubin.cpp
@@ -11,6 +11,7 @@
 #include "mlir/Pass/PassManager.h"
 #include "mlir/Target/NVVMIR.h"
 #include "llvm/Support/TargetSelect.h"
+
 using namespace mlir;
 
 #if MLIR_CUDA_CONVERSIONS_ENABLED
@@ -21,6 +22,7 @@
 }
 
 namespace mlir {
+namespace test {
 void registerTestConvertGPUKernelToCubinPass() {
   PassPipelineRegistration<>(
       "test-kernel-to-cubin",
@@ -37,5 +39,6 @@
             "nvptx64-nvidia-cuda", "sm_35", "+ptx60", "nvvm.cubin"));
       });
 }
+} // namespace test
 } // namespace mlir
 #endif
diff --git a/mlir/test/lib/Transforms/TestConvertGPUKernelToHsaco.cpp b/mlir/test/lib/Transforms/TestConvertGPUKernelToHsaco.cpp
--- a/mlir/test/lib/Transforms/TestConvertGPUKernelToHsaco.cpp
+++ b/mlir/test/lib/Transforms/TestConvertGPUKernelToHsaco.cpp
@@ -11,6 +11,7 @@
 #include "mlir/Pass/PassManager.h"
 #include "mlir/Target/ROCDLIR.h"
 #include "llvm/Support/TargetSelect.h"
+
 using namespace mlir;
 
 #if MLIR_ROCM_CONVERSIONS_ENABLED
@@ -21,6 +22,7 @@
 }
 
 namespace mlir {
+namespace test {
 void registerTestConvertGPUKernelToHsacoPass() {
   PassPipelineRegistration<>(
       "test-kernel-to-hsaco",
@@ -37,5 +39,6 @@
             "amdgcn-amd-amdhsa", "gfx900", "-code-object-v3", "rocdl.hsaco"));
       });
 }
+} // namespace test
 } // namespace mlir
 #endif
diff --git a/mlir/test/lib/Transforms/TestDominance.cpp b/mlir/test/lib/Transforms/TestDominance.cpp
--- a/mlir/test/lib/Transforms/TestDominance.cpp
+++ b/mlir/test/lib/Transforms/TestDominance.cpp
@@ -82,9 +82,11 @@
 } // end anonymous namespace
 
 namespace mlir {
+namespace test {
 void registerTestDominancePass() {
   PassRegistration<TestDominancePass>(
       "test-print-dominance",
       "Print the dominance information for multiple regions.");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestDynamicPipeline.cpp b/mlir/test/lib/Transforms/TestDynamicPipeline.cpp
--- a/mlir/test/lib/Transforms/TestDynamicPipeline.cpp
+++ b/mlir/test/lib/Transforms/TestDynamicPipeline.cpp
@@ -103,12 +103,14 @@
       *this, "op-name", llvm::cl::MiscFlags::CommaSeparated,
       llvm::cl::desc("List of function name to apply the pipeline to")};
 };
-} // end namespace
+} // namespace
 
 namespace mlir {
+namespace test {
 void registerTestDynamicPipelinePass() {
   PassRegistration<TestDynamicPipelinePass>(
       "test-dynamic-pipeline", "Tests the dynamic pipeline feature by applying "
                                "a pipeline on a selected set of functions");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestExpandMemRefReshape.cpp b/mlir/test/lib/Transforms/TestExpandMemRefReshape.cpp
--- a/mlir/test/lib/Transforms/TestExpandMemRefReshape.cpp
+++ b/mlir/test/lib/Transforms/TestExpandMemRefReshape.cpp
@@ -30,8 +30,10 @@
 }
 
 namespace mlir {
+namespace test {
 void registerTestExpandMemRefReshapePass() {
   PassRegistration<TestExpandMemRefReshapePass> pass(
       "test-expand-memref-reshape", "Test expanding memref reshape");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestExpandTanh.cpp b/mlir/test/lib/Transforms/TestExpandTanh.cpp
--- a/mlir/test/lib/Transforms/TestExpandTanh.cpp
+++ b/mlir/test/lib/Transforms/TestExpandTanh.cpp
@@ -30,8 +30,10 @@
 }
 
 namespace mlir {
+namespace test {
 void registerTestExpandTanhPass() {
   PassRegistration<TestExpandTanhPass> pass("test-expand-tanh",
                                             "Test expanding tanh");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestFinalizingBufferize.cpp b/mlir/test/lib/Transforms/TestFinalizingBufferize.cpp
--- a/mlir/test/lib/Transforms/TestFinalizingBufferize.cpp
+++ b/mlir/test/lib/Transforms/TestFinalizingBufferize.cpp
@@ -50,15 +50,15 @@
   /// Converts tensor based test operations to buffer based ones using
   /// bufferize.
   class TensorBasedOpConverter
-      : public BufferizeOpConversionPattern<mlir::TensorBasedOp> {
+      : public BufferizeOpConversionPattern<test::TensorBasedOp> {
   public:
     using BufferizeOpConversionPattern<
-        mlir::TensorBasedOp>::BufferizeOpConversionPattern;
+        test::TensorBasedOp>::BufferizeOpConversionPattern;
 
     LogicalResult
-    matchAndRewrite(mlir::TensorBasedOp op, ArrayRef<Value> operands,
+    matchAndRewrite(test::TensorBasedOp op, ArrayRef<Value> operands,
                     ConversionPatternRewriter &rewriter) const final {
-      mlir::TensorBasedOpAdaptor adaptor(
+      mlir::test::TensorBasedOpAdaptor adaptor(
           operands, op.getOperation()->getAttrDictionary());
 
       // The input needs to be turned into a buffer first. Until then, bail out.
@@ -76,9 +76,9 @@
       Value newOutputBuffer = rewriter.create<AllocOp>(loc, memrefType);
 
       // Generate a new test operation that works on buffers.
-      rewriter.create<mlir::BufferBasedOp>(loc,
-                                           /*input=*/adaptor.input(),
-                                           /*output=*/newOutputBuffer);
+      rewriter.create<mlir::test::BufferBasedOp>(loc,
+                                                 /*input=*/adaptor.input(),
+                                                 /*output=*/newOutputBuffer);
 
       // Replace the results of the old op with the new output buffers.
       rewriter.replaceOp(op, newOutputBuffer);
@@ -87,7 +87,7 @@
   };
 
   void getDependentDialects(DialectRegistry &registry) const override {
-    registry.insert<TestDialect>();
+    registry.insert<test::TestDialect>();
   }
 
   void runOnOperation() override {
@@ -97,8 +97,8 @@
 
     // Mark all Standard operations legal.
     target.addLegalDialect<StandardOpsDialect>();
-    target.addLegalOp<MakeTupleOp>();
-    target.addLegalOp<GetTupleElementOp>();
+    target.addLegalOp<test::MakeTupleOp>();
+    target.addLegalOp<test::GetTupleElementOp>();
     target.addLegalOp<ModuleOp>();
     target.addLegalOp<ModuleTerminatorOp>();
 
@@ -106,7 +106,7 @@
     auto isLegalOperation = [&](Operation *op) {
       return converter.isLegal(op);
     };
-    target.addDynamicallyLegalDialect<TestDialect>(isLegalOperation);
+    target.addDynamicallyLegalDialect<test::TestDialect>(isLegalOperation);
 
     // Mark Standard Return operations illegal as long as one operand is tensor.
     target.addDynamicallyLegalOp<mlir::ReturnOp>([&](mlir::ReturnOp returnOp) {
@@ -144,7 +144,8 @@
           TypeRange TypeRange = inputs.getTypes();
           SmallVector<Type, 2> types(TypeRange.begin(), TypeRange.end());
           TupleType tuple = TupleType::get(types, builder.getContext());
-          mlir::Value value = builder.create<MakeTupleOp>(loc, tuple, inputs);
+          mlir::Value value =
+              builder.create<test::MakeTupleOp>(loc, tuple, inputs);
           return value;
         });
 
@@ -152,7 +153,7 @@
                                              TupleType resultType, Value value,
                                              SmallVectorImpl<Value> &values) {
       for (unsigned i = 0, e = resultType.size(); i < e; ++i) {
-        Value res = builder.create<GetTupleElementOp>(
+        Value res = builder.create<test::GetTupleElementOp>(
             loc, resultType.getType(i), value, builder.getI32IntegerAttr(i));
         values.push_back(res);
       }
@@ -160,8 +161,7 @@
     });
 
     OwningRewritePatternList patterns;
-    populateWithBufferizeOpConversionPatterns<mlir::ReturnOp, mlir::ReturnOp,
-                                              mlir::CopyOp>(
+    populateWithBufferizeOpConversionPatterns<ReturnOp, ReturnOp, test::CopyOp>(
         &context, converter, patterns);
     patterns.insert<TensorBasedOpConverter>(&context, converter);
 
@@ -173,6 +173,7 @@
 } // end anonymous namespace
 
 namespace mlir {
+namespace test {
 void registerTestFinalizingBufferizePass() {
   PassRegistration<
       TestFinalizingBufferizePass</*allowMemrefFunctionResults=*/false>>(
@@ -186,4 +187,5 @@
       "Tests finalizing buffierize conversions, allowing functions to have "
       "memref typed results.");
 }
-} // end namespace mlir
+} // namespace test
+} // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestGpuParallelLoopMapping.cpp b/mlir/test/lib/Transforms/TestGpuParallelLoopMapping.cpp
--- a/mlir/test/lib/Transforms/TestGpuParallelLoopMapping.cpp
+++ b/mlir/test/lib/Transforms/TestGpuParallelLoopMapping.cpp
@@ -28,12 +28,14 @@
       greedilyMapParallelSCFToGPU(region);
   }
 };
-} // end namespace
+} // namespace
 
 namespace mlir {
+namespace test {
 void registerTestGpuParallelLoopMappingPass() {
   PassRegistration<TestGpuGreedyParallelLoopMappingPass> registration(
       "test-gpu-greedy-parallel-loop-mapping",
       "Greedily maps all parallel loops to gpu hardware ids.");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestInlining.cpp b/mlir/test/lib/Transforms/TestInlining.cpp
--- a/mlir/test/lib/Transforms/TestInlining.cpp
+++ b/mlir/test/lib/Transforms/TestInlining.cpp
@@ -22,6 +22,7 @@
 #include "llvm/ADT/StringSet.h"
 
 using namespace mlir;
+using namespace mlir::test;
 
 namespace {
 struct Inliner : public PassWrapper<Inliner, FunctionPass> {
@@ -61,7 +62,9 @@
 } // end anonymous namespace
 
 namespace mlir {
+namespace test {
 void registerInliner() {
   PassRegistration<Inliner>("test-inline", "Test inlining region calls");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestLinalgCodegenStrategy.cpp b/mlir/test/lib/Transforms/TestLinalgCodegenStrategy.cpp
--- a/mlir/test/lib/Transforms/TestLinalgCodegenStrategy.cpp
+++ b/mlir/test/lib/Transforms/TestLinalgCodegenStrategy.cpp
@@ -143,8 +143,10 @@
 }
 
 namespace mlir {
+namespace test {
 void registerTestLinalgCodegenStrategy() {
   PassRegistration<TestLinalgCodegenStrategy> testLinalgCodegenStrategyPass(
       "test-linalg-codegen-strategy", "Test Linalg Codegen Strategy.");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestLinalgFusionTransforms.cpp b/mlir/test/lib/Transforms/TestLinalgFusionTransforms.cpp
--- a/mlir/test/lib/Transforms/TestLinalgFusionTransforms.cpp
+++ b/mlir/test/lib/Transforms/TestLinalgFusionTransforms.cpp
@@ -188,6 +188,7 @@
 } // namespace
 
 namespace mlir {
+namespace test {
 void registerTestLinalgFusionTransforms() {
   PassRegistration<TestLinalgFusionTransforms> testFusionTransformsPass(
       "test-linalg-fusion-transform-patterns",
@@ -198,4 +199,5 @@
       "test-linalg-greedy-fusion",
       "Test Linalg fusion by applying a greedy test transformation.");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestLinalgHoisting.cpp b/mlir/test/lib/Transforms/TestLinalgHoisting.cpp
--- a/mlir/test/lib/Transforms/TestLinalgHoisting.cpp
+++ b/mlir/test/lib/Transforms/TestLinalgHoisting.cpp
@@ -52,8 +52,10 @@
 }
 
 namespace mlir {
+namespace test {
 void registerTestLinalgHoisting() {
   PassRegistration<TestLinalgHoisting> testTestLinalgHoistingPass(
       "test-linalg-hoisting", "Test Linalg hoisting functions.");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestLinalgTransforms.cpp b/mlir/test/lib/Transforms/TestLinalgTransforms.cpp
--- a/mlir/test/lib/Transforms/TestLinalgTransforms.cpp
+++ b/mlir/test/lib/Transforms/TestLinalgTransforms.cpp
@@ -503,9 +503,11 @@
 }
 
 namespace mlir {
+namespace test {
 void registerTestLinalgTransforms() {
   PassRegistration<TestLinalgTransforms> testTransformPatternsPass(
       "test-linalg-transform-patterns",
       "Test Linalg transformation patterns by applying them greedily.");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestLiveness.cpp b/mlir/test/lib/Transforms/TestLiveness.cpp
--- a/mlir/test/lib/Transforms/TestLiveness.cpp
+++ b/mlir/test/lib/Transforms/TestLiveness.cpp
@@ -29,9 +29,11 @@
 } // end anonymous namespace
 
 namespace mlir {
+namespace test {
 void registerTestLivenessPass() {
   PassRegistration<TestLivenessPass>(
       "test-print-liveness",
       "Print the contents of a constructed liveness information.");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestLoopFusion.cpp b/mlir/test/lib/Transforms/TestLoopFusion.cpp
--- a/mlir/test/lib/Transforms/TestLoopFusion.cpp
+++ b/mlir/test/lib/Transforms/TestLoopFusion.cpp
@@ -192,8 +192,10 @@
 }
 
 namespace mlir {
+namespace test {
 void registerTestLoopFusion() {
   PassRegistration<TestLoopFusion>("test-loop-fusion",
                                    "Tests loop fusion utility functions.");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestLoopMapping.cpp b/mlir/test/lib/Transforms/TestLoopMapping.cpp
--- a/mlir/test/lib/Transforms/TestLoopMapping.cpp
+++ b/mlir/test/lib/Transforms/TestLoopMapping.cpp
@@ -49,12 +49,14 @@
     });
   }
 };
-} // end namespace
+} // namespace
 
 namespace mlir {
+namespace test {
 void registerTestLoopMappingPass() {
   PassRegistration<TestLoopMappingPass>(
       "test-mapping-to-processing-elements",
       "test mapping a single loop on a virtual processor grid");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestLoopParametricTiling.cpp b/mlir/test/lib/Transforms/TestLoopParametricTiling.cpp
--- a/mlir/test/lib/Transforms/TestLoopParametricTiling.cpp
+++ b/mlir/test/lib/Transforms/TestLoopParametricTiling.cpp
@@ -46,13 +46,15 @@
       llvm::cl::desc(
           "fixed number of iterations that the outer loops should have")};
 };
-} // end namespace
+} // namespace
 
 namespace mlir {
+namespace test {
 void registerSimpleParametricTilingPass() {
   PassRegistration<SimpleParametricLoopTilingPass>(
       "test-extract-fixed-outer-loops",
       "test application of parametric tiling to the outer loops so that the "
       "ranges of outer loops become static");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestLoopUnrolling.cpp b/mlir/test/lib/Transforms/TestLoopUnrolling.cpp
--- a/mlir/test/lib/Transforms/TestLoopUnrolling.cpp
+++ b/mlir/test/lib/Transforms/TestLoopUnrolling.cpp
@@ -61,11 +61,13 @@
   Option<unsigned> loopDepth{*this, "loop-depth", llvm::cl::desc("Loop depth."),
                              llvm::cl::init(0)};
 };
-} // end namespace
+} // namespace
 
 namespace mlir {
+namespace test {
 void registerTestLoopUnrollingPass() {
   PassRegistration<TestLoopUnrollingPass>(
       "test-loop-unrolling", "Tests loop unrolling transformation");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestMemRefBoundCheck.cpp b/mlir/test/lib/Transforms/TestMemRefBoundCheck.cpp
--- a/mlir/test/lib/Transforms/TestMemRefBoundCheck.cpp
+++ b/mlir/test/lib/Transforms/TestMemRefBoundCheck.cpp
@@ -46,8 +46,10 @@
 }
 
 namespace mlir {
+namespace test {
 void registerMemRefBoundCheck() {
   PassRegistration<TestMemRefBoundCheck>(
       "test-memref-bound-check", "Check memref access bounds in a Function");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestMemRefDependenceCheck.cpp b/mlir/test/lib/Transforms/TestMemRefDependenceCheck.cpp
--- a/mlir/test/lib/Transforms/TestMemRefDependenceCheck.cpp
+++ b/mlir/test/lib/Transforms/TestMemRefDependenceCheck.cpp
@@ -111,9 +111,11 @@
 }
 
 namespace mlir {
+namespace test {
 void registerTestMemRefDependenceCheck() {
   PassRegistration<TestMemRefDependenceCheck> pass(
       "test-memref-dependence-check",
       "Checks dependences between all pairs of memref accesses.");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestMemRefStrideCalculation.cpp b/mlir/test/lib/Transforms/TestMemRefStrideCalculation.cpp
--- a/mlir/test/lib/Transforms/TestMemRefStrideCalculation.cpp
+++ b/mlir/test/lib/Transforms/TestMemRefStrideCalculation.cpp
@@ -50,8 +50,10 @@
 }
 
 namespace mlir {
+namespace test {
 void registerTestMemRefStrideCalculation() {
   PassRegistration<TestMemRefStrideCalculation> pass(
       "test-memref-stride-calculation", "Test operation constant folding");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestOpaqueLoc.cpp b/mlir/test/lib/Transforms/TestOpaqueLoc.cpp
--- a/mlir/test/lib/Transforms/TestOpaqueLoc.cpp
+++ b/mlir/test/lib/Transforms/TestOpaqueLoc.cpp
@@ -82,8 +82,10 @@
 } // end anonymous namespace
 
 namespace mlir {
+namespace test {
 void registerTestOpaqueLoc() {
   PassRegistration<TestOpaqueLoc> pass(
       "test-opaque-loc", "Changes all leaf locations to opaque locations");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestSCFUtils.cpp b/mlir/test/lib/Transforms/TestSCFUtils.cpp
--- a/mlir/test/lib/Transforms/TestSCFUtils.cpp
+++ b/mlir/test/lib/Transforms/TestSCFUtils.cpp
@@ -68,13 +68,15 @@
     });
   }
 };
-} // end namespace
+} // namespace
 
 namespace mlir {
+namespace test {
 void registerTestSCFUtilsPass() {
   PassRegistration<TestSCFForUtilsPass>("test-scf-for-utils",
                                         "test scf.for utils");
   PassRegistration<TestSCFIfUtilsPass>("test-scf-if-utils",
                                        "test scf.if utils");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/test/lib/Transforms/TestVectorTransforms.cpp b/mlir/test/lib/Transforms/TestVectorTransforms.cpp
--- a/mlir/test/lib/Transforms/TestVectorTransforms.cpp
+++ b/mlir/test/lib/Transforms/TestVectorTransforms.cpp
@@ -294,6 +294,7 @@
 } // end anonymous namespace
 
 namespace mlir {
+namespace test {
 void registerTestVectorConversions() {
   PassRegistration<TestVectorToVectorConversion> vectorToVectorPass(
       "test-vector-to-vector-conversion",
@@ -327,4 +328,5 @@
       "test-vector-to-forloop",
       "Test conversion patterns to break up a vector op into a for loop");
 }
+} // namespace test
 } // namespace mlir
diff --git a/mlir/tools/mlir-opt/mlir-opt.cpp b/mlir/tools/mlir-opt/mlir-opt.cpp
--- a/mlir/tools/mlir-opt/mlir-opt.cpp
+++ b/mlir/tools/mlir-opt/mlir-opt.cpp
@@ -27,36 +27,47 @@
 using namespace llvm;
 using namespace mlir;
 
-namespace mlir {
 // Defined in the test directory, no public header.
-void registerConvertCallOpPass();
+namespace mlir {
 void registerConvertToTargetEnvPass();
-void registerInliner();
-void registerMemRefBoundCheck();
 void registerPassManagerTestPass();
-void registerPatternsTestPass();
 void registerPrintOpAvailabilityPass();
 void registerSideEffectTestPasses();
-void registerSimpleParametricTilingPass();
 void registerSliceAnalysisTestPass();
 void registerSymbolTestPasses();
 void registerTestAffineDataCopyPass();
-void registerTestAffineLoopParametricTilingPass();
 void registerTestAffineLoopUnswitchingPass();
 void registerTestAllReduceLoweringPass();
+void registerTestFunc();
+void registerTestGpuMemoryPromotionPass();
+void registerTestLoopPermutationPass();
+void registerTestMatchers();
+void registerTestPrintDefUsePass();
+void registerTestPrintNestingPass();
+void registerTestReducer();
+void registerTestSpirvEntryPointABIPass();
+void registerTestSpirvModuleCombinerPass();
+void registerTestTraitsPass();
+void registerVectorizerTestPass();
+
+namespace test {
+void registerConvertCallOpPass();
+void registerInliner();
+void registerMemRefBoundCheck();
+void registerPatternsTestPass();
+void registerSimpleParametricTilingPass();
+void registerTestAffineLoopParametricTilingPass();
 void registerTestCallGraphPass();
 void registerTestConstantFold();
 void registerTestConvVectorization();
 void registerTestConvertGPUKernelToCubinPass();
 void registerTestConvertGPUKernelToHsacoPass();
-void registerTestDominancePass();
 void registerTestDialect(DialectRegistry &);
+void registerTestDominancePass();
 void registerTestDynamicPipelinePass();
 void registerTestExpandMemRefReshapePass();
 void registerTestExpandTanhPass();
 void registerTestFinalizingBufferizePass();
-void registerTestFunc();
-void registerTestGpuMemoryPromotionPass();
 void registerTestGpuParallelLoopMappingPass();
 void registerTestInterfaces();
 void registerTestLinalgCodegenStrategy();
@@ -67,85 +78,78 @@
 void registerTestLivenessPass();
 void registerTestLoopFusion();
 void registerTestLoopMappingPass();
-void registerTestLoopPermutationPass();
 void registerTestLoopUnrollingPass();
-void registerTestMatchers();
 void registerTestMemRefDependenceCheck();
 void registerTestMemRefStrideCalculation();
 void registerTestOpaqueLoc();
 void registerTestPreparationPassWithAllowedMemrefResults();
-void registerTestPrintDefUsePass();
-void registerTestPrintNestingPass();
 void registerTestRecursiveTypesPass();
-void registerTestReducer();
-void registerTestSpirvEntryPointABIPass();
-void registerTestSpirvModuleCombinerPass();
 void registerTestSCFUtilsPass();
-void registerTestTraitsPass();
 void registerTestVectorConversions();
-void registerVectorizerTestPass();
+} // namespace test
 } // namespace mlir
 
 #ifdef MLIR_INCLUDE_TESTS
 void registerTestPasses() {
-  registerConvertCallOpPass();
   registerConvertToTargetEnvPass();
-  registerInliner();
-  registerMemRefBoundCheck();
   registerPassManagerTestPass();
-  registerPatternsTestPass();
   registerPrintOpAvailabilityPass();
   registerSideEffectTestPasses();
-  registerSimpleParametricTilingPass();
   registerSliceAnalysisTestPass();
   registerSymbolTestPasses();
   registerTestAffineDataCopyPass();
-  registerTestAllReduceLoweringPass();
   registerTestAffineLoopUnswitchingPass();
-  registerTestLoopPermutationPass();
-  registerTestCallGraphPass();
-  registerTestConvVectorization();
-  registerTestConstantFold();
-#if MLIR_CUDA_CONVERSIONS_ENABLED
-  registerTestConvertGPUKernelToCubinPass();
-#endif
-#if MLIR_ROCM_CONVERSIONS_ENABLED
-  registerTestConvertGPUKernelToHsacoPass();
-#endif
-  registerTestAffineLoopParametricTilingPass();
-  registerTestDominancePass();
-  registerTestDynamicPipelinePass();
-  registerTestFinalizingBufferizePass();
+  registerTestAllReduceLoweringPass();
   registerTestFunc();
-  registerTestExpandTanhPass();
-  registerTestExpandMemRefReshapePass();
   registerTestGpuMemoryPromotionPass();
-  registerTestInterfaces();
-  registerTestLinalgCodegenStrategy();
-  registerTestLinalgFusionTransforms();
-  registerTestLinalgGreedyFusion();
-  registerTestLinalgHoisting();
-  registerTestLinalgTransforms();
-  registerTestLivenessPass();
-  registerTestLoopFusion();
-  registerTestLoopMappingPass();
-  registerTestLoopUnrollingPass();
+  registerTestLoopPermutationPass();
   registerTestMatchers();
-  registerTestMemRefDependenceCheck();
-  registerTestMemRefStrideCalculation();
-  registerTestOpaqueLoc();
-  registerTestPreparationPassWithAllowedMemrefResults();
   registerTestPrintDefUsePass();
   registerTestPrintNestingPass();
-  registerTestRecursiveTypesPass();
   registerTestReducer();
-  registerTestGpuParallelLoopMappingPass();
   registerTestSpirvEntryPointABIPass();
   registerTestSpirvModuleCombinerPass();
-  registerTestSCFUtilsPass();
   registerTestTraitsPass();
-  registerTestVectorConversions();
   registerVectorizerTestPass();
+
+  test::registerConvertCallOpPass();
+  test::registerInliner();
+  test::registerMemRefBoundCheck();
+  test::registerPatternsTestPass();
+  test::registerSimpleParametricTilingPass();
+  test::registerTestAffineLoopParametricTilingPass();
+  test::registerTestCallGraphPass();
+  test::registerTestConstantFold();
+#if MLIR_CUDA_CONVERSIONS_ENABLED
+  test::registerTestConvertGPUKernelToCubinPass();
+#endif
+#if MLIR_ROCM_CONVERSIONS_ENABLED
+  test::registerTestConvertGPUKernelToHsacoPass();
+#endif
+  test::registerTestConvVectorization();
+  test::registerTestDominancePass();
+  test::registerTestDynamicPipelinePass();
+  test::registerTestExpandMemRefReshapePass();
+  test::registerTestExpandTanhPass();
+  test::registerTestFinalizingBufferizePass();
+  test::registerTestGpuParallelLoopMappingPass();
+  test::registerTestInterfaces();
+  test::registerTestLinalgCodegenStrategy();
+  test::registerTestLinalgFusionTransforms();
+  test::registerTestLinalgGreedyFusion();
+  test::registerTestLinalgHoisting();
+  test::registerTestLinalgTransforms();
+  test::registerTestLivenessPass();
+  test::registerTestLoopFusion();
+  test::registerTestLoopMappingPass();
+  test::registerTestLoopUnrollingPass();
+  test::registerTestMemRefDependenceCheck();
+  test::registerTestMemRefStrideCalculation();
+  test::registerTestOpaqueLoc();
+  test::registerTestPreparationPassWithAllowedMemrefResults();
+  test::registerTestRecursiveTypesPass();
+  test::registerTestSCFUtilsPass();
+  test::registerTestVectorConversions();
 }
 #endif
 
@@ -157,7 +161,7 @@
   DialectRegistry registry;
   registerAllDialects(registry);
 #ifdef MLIR_INCLUDE_TESTS
-  registerTestDialect(registry);
+  test::registerTestDialect(registry);
 #endif
   return failed(MlirOptMain(argc, argv, "MLIR modular optimizer driver\n",
                             registry,