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
@@ -1359,7 +1359,7 @@
 }
 
 def LLVM_ConstantOp
-    : LLVM_Op<"mlir.constant", [NoSideEffect]>,
+    : LLVM_Op<"mlir.constant", [NoSideEffect, ConstantLike]>,
       LLVM_Builder<[{$res = getLLVMConstant($_resultType, $value, $_location,
                                             moduleTranslation);}]>
 {
@@ -1398,6 +1398,7 @@
   let builders = [LLVM_OneResultOpBuilder];
   let assemblyFormat = "`(` $value `)` attr-dict `:` type($res)";
   let verifier = [{ return ::verify(*this); }];
+  let hasFolder = 1;
 }
 
 // Operations that correspond to LLVM intrinsics. With MLIR operation set being
diff --git a/mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp b/mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp
--- a/mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp
+++ b/mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp
@@ -2085,6 +2085,9 @@
   return success();
 }
 
+// Constant op constant-folds to its value.
+OpFoldResult LLVM::ConstantOp::fold(ArrayRef<Attribute>) { return getValue(); }
+
 //===----------------------------------------------------------------------===//
 // Utility functions for parsing atomic ops
 //===----------------------------------------------------------------------===//
diff --git a/mlir/test/Dialect/LLVMIR/canonicalize.mlir b/mlir/test/Dialect/LLVMIR/canonicalize.mlir
--- a/mlir/test/Dialect/LLVMIR/canonicalize.mlir
+++ b/mlir/test/Dialect/LLVMIR/canonicalize.mlir
@@ -38,3 +38,20 @@
 
   llvm.return %3 : f32
 }
+
+// -----
+
+// Check that LLVM constants participate in cross-dialect constant folding. The
+// resulting constant is created in the arith dialect because the last folded
+// operation belongs to it.
+// CHECK-LABEL: llvm_constant
+func @llvm_constant() -> i32 {
+  // CHECK-NOT: llvm.mlir.constant
+  %0 = llvm.mlir.constant(40 : i32) : i32
+  %1 = llvm.mlir.constant(42 : i32) : i32
+  // CHECK: %[[RES:.*]] = arith.constant 82 : i32
+  // CHECK-NOT: arith.addi
+  %2 = arith.addi %0, %1 : i32
+  // CHECK: return %[[RES]]
+  return %2 : i32
+}