diff --git a/mlir/docs/Dialects/LLVM.md b/mlir/docs/Dialects/LLVM.md
--- a/mlir/docs/Dialects/LLVM.md
+++ b/mlir/docs/Dialects/LLVM.md
@@ -105,6 +105,7 @@
 are produced by dedicated operations that have the corresponding semantics:
 [`llvm.mlir.constant`](#llvmmlirconstant-mlirllvmconstantop),
 [`llvm.mlir.undef`](#llvmmlirundef-mlirllvmundefop),
+[`llvm.mlir.poison`](#llvmmlirpoison-mlirllvmpoisonop),
 [`llvm.mlir.null`](#llvmmlirnull-mlirllvmnullop). Note how these operations are
 prefixed with `mlir.` to indicate that they don't belong to LLVM IR but are only
 necessary to model it in MLIR. The values produced by these operations are
diff --git a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
--- a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
+++ b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
@@ -1652,7 +1652,7 @@
     Unlike LLVM IR, MLIR does not have first-class undefined values. Such values
     must be created as SSA values using `llvm.mlir.undef`. This operation has no
     operands or attributes. It creates an undefined value of the specified LLVM
-    IR dialect type wrapping an LLVM IR structure type.
+    IR dialect type.
 
     Example:
 
@@ -1666,6 +1666,28 @@
   let assemblyFormat = "attr-dict `:` type($res)";
 }
 
+def LLVM_PoisonOp : LLVM_Op<"mlir.poison", [Pure]>,
+                    LLVM_Builder<"$res = llvm::PoisonValue::get($_resultType);"> {
+  let summary = "Creates a poison value of LLVM dialect type.";
+  let description = [{
+    Unlike LLVM IR, MLIR does not have first-class poison values. Such values
+    must be created as SSA values using `llvm.mlir.poison`. This operation has
+    no operands or attributes. It creates a poison value of the specified LLVM
+    IR dialect type.
+
+    Example:
+
+    ```mlir
+    // Create a poison value for a structure with a 32-bit integer followed
+    // by a float.
+    %0 = llvm.mlir.poison : !llvm.struct<(i32, f32)>
+    ```
+  }];
+  let results = (outs LLVM_Type:$res);
+  let builders = [LLVM_OneResultOpBuilder];
+  let assemblyFormat = "attr-dict `:` type($res)";
+}
+
 def LLVM_ConstantOp
     : LLVM_Op<"mlir.constant", [Pure, ConstantLike]>,
       LLVM_Builder<[{$res = getLLVMConstant($_resultType, $value, $_location,
diff --git a/mlir/lib/Target/LLVMIR/ModuleImport.cpp b/mlir/lib/Target/LLVMIR/ModuleImport.cpp
--- a/mlir/lib/Target/LLVMIR/ModuleImport.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleImport.cpp
@@ -1036,6 +1036,12 @@
     return builder.create<NullOp>(loc, type).getResult();
   }
 
+  // Convert poison.
+  if (auto *poisonVal = dyn_cast<llvm::PoisonValue>(constant)) {
+    Type type = convertType(poisonVal->getType());
+    return builder.create<PoisonOp>(loc, type).getResult();
+  }
+
   // Convert undef.
   if (auto *undefVal = dyn_cast<llvm::UndefValue>(constant)) {
     Type type = convertType(undefVal->getType());
diff --git a/mlir/test/Dialect/LLVMIR/roundtrip.mlir b/mlir/test/Dialect/LLVMIR/roundtrip.mlir
--- a/mlir/test/Dialect/LLVMIR/roundtrip.mlir
+++ b/mlir/test/Dialect/LLVMIR/roundtrip.mlir
@@ -438,10 +438,14 @@
 func.func @useFreezeOp(%arg0: i32) {
   // CHECK:  = llvm.freeze %[[ARG0:.*]] : i32
   %0 = llvm.freeze %arg0 : i32
-  // CHECK: %[[x:.*]] = llvm.mlir.undef : i8
+  // CHECK: %[[UNDEF:.*]] = llvm.mlir.undef : i8
   %1 = llvm.mlir.undef : i8
-  // CHECK:  = llvm.freeze %[[x]] : i8
+  // CHECK:  = llvm.freeze %[[UNDEF]] : i8
   %2 = llvm.freeze %1 : i8
+  // CHECK: %[[POISON:.*]] = llvm.mlir.poison : i8
+  %3 = llvm.mlir.poison : i8
+  // CHECK:  = llvm.freeze %[[POISON]] : i8
+  %4 = llvm.freeze %3 : i8
   return
 }
 
diff --git a/mlir/test/Target/LLVMIR/Import/instructions.ll b/mlir/test/Target/LLVMIR/Import/instructions.ll
--- a/mlir/test/Target/LLVMIR/Import/instructions.ll
+++ b/mlir/test/Target/LLVMIR/Import/instructions.ll
@@ -523,10 +523,13 @@
 ; CHECK-SAME:  %[[ARG1:[a-zA-Z0-9]+]]
 define void @freeze(i32 %arg1) {
   ; CHECK:  %[[UNDEF:[0-9]+]] = llvm.mlir.undef : i64
+  ; CHECK:  %[[POISON:[0-9]+]] = llvm.mlir.poison : i16
   ; CHECK:  llvm.freeze %[[ARG1]] : i32
   ; CHECK:  llvm.freeze %[[UNDEF]] : i64
+  ; CHECK:  llvm.freeze %[[POISON]] : i16
   %1 = freeze i32 %arg1
   %2 = freeze i64 undef
+  %3 = freeze i16 poison
   ret void
 }
 
diff --git a/mlir/test/Target/LLVMIR/llvmir.mlir b/mlir/test/Target/LLVMIR/llvmir.mlir
--- a/mlir/test/Target/LLVMIR/llvmir.mlir
+++ b/mlir/test/Target/LLVMIR/llvmir.mlir
@@ -1618,6 +1618,9 @@
   %1 = llvm.mlir.undef : i32
   // CHECK: freeze i32 undef
   %2 = llvm.freeze %1 : i32
+  %3 = llvm.mlir.poison : i32
+  // CHECK: freeze i32 poison
+  %4 = llvm.freeze %3 : i32
   llvm.return
 }