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
@@ -457,6 +457,11 @@
     }]>];
   let assemblyFormat = "operands attr-dict `:` type($condition) `,` type($res)";
 }
+def LLVM_FreezeOp : LLVM_OneResultOp<"freeze", [SameOperandsAndResultType]>,
+                    Arguments<(ins LLVM_Type:$val)> {
+  let assemblyFormat = "$val attr-dict `:` type($val)";
+  string llvmBuilder = "builder.CreateFreeze($val);";
+}
 
 // Terminators.
 def LLVM_BrOp : LLVM_TerminatorOp<"br", []> {
diff --git a/mlir/lib/Target/LLVMIR/ConvertFromLLVMIR.cpp b/mlir/lib/Target/LLVMIR/ConvertFromLLVMIR.cpp
--- a/mlir/lib/Target/LLVMIR/ConvertFromLLVMIR.cpp
+++ b/mlir/lib/Target/LLVMIR/ConvertFromLLVMIR.cpp
@@ -426,6 +426,12 @@
     i->deleteValue();
     return instMap[c] = instMap[i];
   }
+  if (auto *ue = dyn_cast<llvm::UndefValue>(c)) {
+    LLVMType type = processType(ue->getType());
+    if (!type)
+      return nullptr;
+    return instMap[c] = bEntry.create<UndefOp>(UnknownLoc::get(context), type);
+  }
   emitError(unknownLoc) << "unhandled constant: " << diag(*c);
   return nullptr;
 }
@@ -493,7 +499,7 @@
     // ICmp is handled specially.
     // FIXME: fcmp
     // PHI is handled specially.
-    INST(Call, Call),
+    INST(Freeze, Freeze), INST(Call, Call),
     // FIXME: select
     // FIXME: vaarg
     // FIXME: extractelement
@@ -591,6 +597,7 @@
   case llvm::Instruction::PtrToInt:
   case llvm::Instruction::IntToPtr:
   case llvm::Instruction::AddrSpaceCast:
+  case llvm::Instruction::Freeze:
   case llvm::Instruction::BitCast: {
     OperationState state(loc, opcMap.lookup(inst->getOpcode()));
     SmallVector<Value, 4> ops;
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
@@ -282,3 +282,14 @@
 ^bb4:
   llvm.return %0 : !llvm.i32
 }
+
+// CHECK-LABEL: @useFreezeOp
+func @useFreezeOp(%arg0: !llvm.i32) {
+  // CHECK:  = llvm.freeze %[[ARG0:.*]] : !llvm.i32
+  %0 = llvm.freeze %arg0 : !llvm.i32
+  // CHECK: %[[x:.*]] = llvm.mlir.undef : !llvm.i8
+  %1 = llvm.mlir.undef : !llvm.i8
+  // CHECK:  = llvm.freeze %[[x]] : !llvm.i8
+  %2 = llvm.freeze %1 : !llvm.i8
+  return
+}
\ No newline at end of file
diff --git a/mlir/test/Target/import.ll b/mlir/test/Target/import.ll
--- a/mlir/test/Target/import.ll
+++ b/mlir/test/Target/import.ll
@@ -297,3 +297,14 @@
   ; CHECK: llvm.return %{{[0-9]+}} : !llvm.i32
   ret i32 0
 }
+
+;CHECK-LABEL: @useFreezeOp
+define i32 @useFreezeOp(i32 %x) {
+  ;CHECK: %{{[0-9]+}} = llvm.freeze %{{[0-9a-z]+}} : !llvm.i32
+  %1 = freeze i32 %x
+  %2 = add i8 10, 10
+  ;CHECK: %{{[0-9]+}} = llvm.freeze %{{[0-9]+}} : !llvm.i8
+  %3 = freeze i8 %2
+  %poison = add nsw i1 0, undef
+  ret i32 0
+}
\ No newline at end of file
diff --git a/mlir/test/Target/llvmir.mlir b/mlir/test/Target/llvmir.mlir
--- a/mlir/test/Target/llvmir.mlir
+++ b/mlir/test/Target/llvmir.mlir
@@ -1171,3 +1171,13 @@
 ^bb3:	// pred: ^bb1
   %8 = llvm.invoke @bar(%6) to ^bb2 unwind ^bb1 : (!llvm<"i8*">) -> !llvm<"i8*">
 }
+
+// CHECK-LABEL: @callFreezeOp
+llvm.func @callFreezeOp(%x : !llvm.i32) {
+  // CHECK: freeze i32 %{{[0-9]+}}
+  %0 = llvm.freeze %x : !llvm.i32
+  %1 = llvm.mlir.undef : !llvm.i32
+  // CHECK: freeze i32 undef 
+  %2 = llvm.freeze %1 : !llvm.i32
+  llvm.return
+}
\ No newline at end of file