diff --git a/mlir/include/mlir/Conversion/Passes.h b/mlir/include/mlir/Conversion/Passes.h
--- a/mlir/include/mlir/Conversion/Passes.h
+++ b/mlir/include/mlir/Conversion/Passes.h
@@ -57,6 +57,7 @@
 #include "mlir/Conversion/TosaToLinalg/TosaToLinalg.h"
 #include "mlir/Conversion/TosaToSCF/TosaToSCF.h"
 #include "mlir/Conversion/TosaToTensor/TosaToTensor.h"
+#include "mlir/Conversion/UBToLLVM/UBToLLVM.h"
 #include "mlir/Conversion/VectorToArmSME/VectorToArmSME.h"
 #include "mlir/Conversion/VectorToGPU/VectorToGPU.h"
 #include "mlir/Conversion/VectorToLLVM/ConvertVectorToLLVM.h"
diff --git a/mlir/include/mlir/Conversion/Passes.td b/mlir/include/mlir/Conversion/Passes.td
--- a/mlir/include/mlir/Conversion/Passes.td
+++ b/mlir/include/mlir/Conversion/Passes.td
@@ -1037,6 +1037,23 @@
   let constructor = "tosa::createTosaToTensor()";
 }
 
+//===----------------------------------------------------------------------===//
+// UBToLLVM
+//===----------------------------------------------------------------------===//
+
+def UBToLLVMConversionPass : Pass<"convert-ub-to-llvm"> {
+  let summary = "Convert UB dialect to LLVM dialect";
+  let description = [{
+    This pass converts supported UB ops to LLVM dialect instructions.
+  }];
+  let dependentDialects = ["LLVM::LLVMDialect"];
+  let options = [
+    Option<"indexBitwidth", "index-bitwidth", "unsigned",
+           /*default=kDeriveIndexBitwidthFromDataLayout*/"0",
+           "Bitwidth of the index type, 0 to use size of machine word">,
+  ];
+}
+
 //===----------------------------------------------------------------------===//
 // VectorToGPU
 //===----------------------------------------------------------------------===//
diff --git a/mlir/include/mlir/Conversion/UBToLLVM/UBToLLVM.h b/mlir/include/mlir/Conversion/UBToLLVM/UBToLLVM.h
new file mode 100644
--- /dev/null
+++ b/mlir/include/mlir/Conversion/UBToLLVM/UBToLLVM.h
@@ -0,0 +1,29 @@
+//===- UBToLLVM.h - UB to LLVM dialect conversion ---------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef MLIR_CONVERSION_UBTOLLVM_UBLLVM_H
+#define MLIR_CONVERSION_UBTOLLVM_UBLLVM_H
+
+#include <memory>
+
+namespace mlir {
+
+class LLVMTypeConverter;
+class RewritePatternSet;
+class Pass;
+
+#define GEN_PASS_DECL_UBTOLLVMCONVERSIONPASS
+#include "mlir/Conversion/Passes.h.inc"
+
+namespace ub {
+void populateUBToLLVMConversionPatterns(LLVMTypeConverter &converter,
+                                        RewritePatternSet &patterns);
+} // namespace ub
+} // namespace mlir
+
+#endif // MLIR_CONVERSION_UBTOLLVM_UBLLVM_H
diff --git a/mlir/lib/Conversion/CMakeLists.txt b/mlir/lib/Conversion/CMakeLists.txt
--- a/mlir/lib/Conversion/CMakeLists.txt
+++ b/mlir/lib/Conversion/CMakeLists.txt
@@ -6,8 +6,8 @@
 add_subdirectory(ArmNeon2dToIntr)
 add_subdirectory(AsyncToLLVM)
 add_subdirectory(BufferizationToMemRef)
-add_subdirectory(ComplexToLLVM)
 add_subdirectory(ComplexToLibm)
+add_subdirectory(ComplexToLLVM)
 add_subdirectory(ComplexToSPIRV)
 add_subdirectory(ComplexToStandard)
 add_subdirectory(ControlFlowToLLVM)
@@ -47,8 +47,9 @@
 add_subdirectory(TosaToLinalg)
 add_subdirectory(TosaToSCF)
 add_subdirectory(TosaToTensor)
+add_subdirectory(UBToLLVM)
 add_subdirectory(VectorToArmSME)
-add_subdirectory(VectorToLLVM)
 add_subdirectory(VectorToGPU)
+add_subdirectory(VectorToLLVM)
 add_subdirectory(VectorToSCF)
 add_subdirectory(VectorToSPIRV)
diff --git a/mlir/lib/Conversion/UBToLLVM/CMakeLists.txt b/mlir/lib/Conversion/UBToLLVM/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/mlir/lib/Conversion/UBToLLVM/CMakeLists.txt
@@ -0,0 +1,17 @@
+add_mlir_conversion_library(MLIRUBToLLVM
+  UBToLLVM.cpp
+
+  ADDITIONAL_HEADER_DIRS
+  ${MLIR_MAIN_INCLUDE_DIR}/mlir/Conversion/UBToLLVM
+
+  DEPENDS
+  MLIRConversionPassIncGen
+
+  LINK_COMPONENTS
+  Core
+
+  LINK_LIBS PUBLIC
+  MLIRLLVMCommonConversion
+  MLIRLLVMDialect
+  MLIRUBDialect
+  )
diff --git a/mlir/lib/Conversion/UBToLLVM/UBToLLVM.cpp b/mlir/lib/Conversion/UBToLLVM/UBToLLVM.cpp
new file mode 100644
--- /dev/null
+++ b/mlir/lib/Conversion/UBToLLVM/UBToLLVM.cpp
@@ -0,0 +1,93 @@
+//===- UBToLLVM.cpp - UB to LLVM dialect conversion -----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Conversion/UBToLLVM/UBToLLVM.h"
+
+#include "mlir/Conversion/LLVMCommon/ConversionTarget.h"
+#include "mlir/Conversion/LLVMCommon/Pattern.h"
+#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
+#include "mlir/Dialect/UB/IR/UBOps.h"
+#include "mlir/IR/TypeUtilities.h"
+#include "mlir/Pass/Pass.h"
+
+namespace mlir {
+#define GEN_PASS_DEF_UBTOLLVMCONVERSIONPASS
+#include "mlir/Conversion/Passes.h.inc"
+} // namespace mlir
+
+using namespace mlir;
+
+namespace {
+
+struct PoisonOpLowering : public ConvertOpToLLVMPattern<ub::PoisonOp> {
+  using ConvertOpToLLVMPattern::ConvertOpToLLVMPattern;
+
+  LogicalResult
+  matchAndRewrite(ub::PoisonOp op, OpAdaptor adaptor,
+                  ConversionPatternRewriter &rewriter) const override;
+};
+
+} // namespace
+
+//===----------------------------------------------------------------------===//
+// PoisonOpLowering
+//===----------------------------------------------------------------------===//
+
+LogicalResult
+PoisonOpLowering::matchAndRewrite(ub::PoisonOp op, OpAdaptor adaptor,
+                                  ConversionPatternRewriter &rewriter) const {
+  Type origType = op.getType();
+  if (!origType.isIntOrIndexOrFloat())
+    return rewriter.notifyMatchFailure(
+        op, [&](Diagnostic &diag) { diag << "unsupported type " << origType; });
+
+  Type resType = getTypeConverter()->convertType(origType);
+  if (!resType)
+    return rewriter.notifyMatchFailure(op, [&](Diagnostic &diag) {
+      diag << "failed to convert result type " << origType;
+    });
+
+  rewriter.replaceOpWithNewOp<LLVM::PoisonOp>(op, resType);
+  return success();
+}
+
+//===----------------------------------------------------------------------===//
+// Pass Definition
+//===----------------------------------------------------------------------===//
+
+namespace {
+struct UBToLLVMConversionPass
+    : public impl::UBToLLVMConversionPassBase<UBToLLVMConversionPass> {
+  using Base::Base;
+
+  void runOnOperation() override {
+    LLVMConversionTarget target(getContext());
+    RewritePatternSet patterns(&getContext());
+
+    LowerToLLVMOptions options(&getContext());
+    if (indexBitwidth != kDeriveIndexBitwidthFromDataLayout)
+      options.overrideIndexBitwidth(indexBitwidth);
+
+    LLVMTypeConverter converter(&getContext(), options);
+    mlir::ub::populateUBToLLVMConversionPatterns(converter, patterns);
+
+    if (failed(applyPartialConversion(getOperation(), target,
+                                      std::move(patterns))))
+      signalPassFailure();
+  }
+};
+} // namespace
+
+//===----------------------------------------------------------------------===//
+// Pattern Population
+//===----------------------------------------------------------------------===//
+
+void mlir::ub::populateUBToLLVMConversionPatterns(LLVMTypeConverter &converter,
+                                                  RewritePatternSet &patterns) {
+  patterns.add<PoisonOpLowering>(converter);
+}
diff --git a/mlir/test/Conversion/UBToLLVM/ub-to-llvm.mlir b/mlir/test/Conversion/UBToLLVM/ub-to-llvm.mlir
new file mode 100644
--- /dev/null
+++ b/mlir/test/Conversion/UBToLLVM/ub-to-llvm.mlir
@@ -0,0 +1,12 @@
+// RUN: mlir-opt -pass-pipeline="builtin.module(func.func(convert-ub-to-llvm))" %s -split-input-file | FileCheck %s
+
+// CHECK-LABEL: @check_poison
+func.func @check_poison() {
+// CHECK: {{.*}} = llvm.mlir.poison : i64
+  %0 = ub.poison : index
+// CHECK: {{.*}} = llvm.mlir.poison : i16
+  %1 = ub.poison : i16
+// CHECK: {{.*}} = llvm.mlir.poison : f64
+  %2 = ub.poison : f64
+  return
+}