diff --git a/mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp b/mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp
--- a/mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp
+++ b/mlir/lib/Conversion/ArithToLLVM/ArithToLLVM.cpp
@@ -13,6 +13,7 @@
 #include "mlir/Conversion/LLVMCommon/VectorPattern.h"
 #include "mlir/Dialect/Arith/IR/Arith.h"
 #include "mlir/Dialect/LLVMIR/LLVMDialect.h"
+#include "mlir/Dialect/UB/IR/UBOps.h"
 #include "mlir/IR/TypeUtilities.h"
 #include "mlir/Pass/Pass.h"
 #include <type_traits>
@@ -173,6 +174,14 @@
                   ConversionPatternRewriter &rewriter) const override;
 };
 
+struct PoisonOpLowering : public ConvertOpToLLVMPattern<ub::PoisonOp> {
+  using ConvertOpToLLVMPattern::ConvertOpToLLVMPattern;
+
+  LogicalResult
+  matchAndRewrite(ub::PoisonOp op, OpAdaptor adaptor,
+                  ConversionPatternRewriter &rewriter) const override;
+};
+
 } // namespace
 
 //===----------------------------------------------------------------------===//
@@ -412,6 +421,30 @@
       rewriter);
 }
 
+//===----------------------------------------------------------------------===//
+// 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 << "only index, integer and float types are supported, got "
+           << 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
 //===----------------------------------------------------------------------===//
@@ -477,6 +510,7 @@
     MulUIExtendedOpLowering,
     NegFOpLowering,
     OrIOpLowering,
+    PoisonOpLowering,
     RemFOpLowering,
     RemSIOpLowering,
     RemUIOpLowering,
diff --git a/mlir/test/Conversion/ArithToLLVM/arith-to-llvm.mlir b/mlir/test/Conversion/ArithToLLVM/arith-to-llvm.mlir
--- a/mlir/test/Conversion/ArithToLLVM/arith-to-llvm.mlir
+++ b/mlir/test/Conversion/ArithToLLVM/arith-to-llvm.mlir
@@ -564,3 +564,17 @@
   %7 = arith.subf %arg0, %arg1 fastmath<fast> : f32
   return
 }
+
+
+// -----
+
+// 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
+}