diff --git a/mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp b/mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp
--- a/mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp
+++ b/mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp
@@ -2402,6 +2402,28 @@
   }
 };
 
+struct RankOpLowering : public ConvertOpToLLVMPattern<RankOp> {
+  using ConvertOpToLLVMPattern<RankOp>::ConvertOpToLLVMPattern;
+
+  LogicalResult
+  matchAndRewrite(Operation *op, ArrayRef<Value> operands,
+                  ConversionPatternRewriter &rewriter) const override {
+    Location loc = op->getLoc();
+    Type operandType = cast<RankOp>(op).memrefOrTensor().getType();
+    if (auto unrankedMemRefType = operandType.dyn_cast<UnrankedMemRefType>()) {
+      UnrankedMemRefDescriptor desc(RankOp::Adaptor(operands).memrefOrTensor());
+      rewriter.replaceOp(op, {desc.rank(rewriter, loc)});
+      return success();
+    }
+    if (auto rankedMemRefType = operandType.dyn_cast<MemRefType>()) {
+      rewriter.replaceOp(
+          op, {createIndexConstant(rewriter, loc, rankedMemRefType.getRank())});
+      return success();
+    }
+    return failure();
+  }
+};
+
 // Common base for load and store operations on MemRefs.  Restricts the match
 // to supported MemRef types.  Provides functionality to emit code accessing a
 // specific element of the underlying data buffer.
@@ -3272,6 +3294,7 @@
       DimOpLowering,
       LoadOpLowering,
       MemRefCastOpLowering,
+      RankOpLowering,
       StoreOpLowering,
       SubViewOpLowering,
       ViewOpLowering,
diff --git a/mlir/test/Conversion/StandardToLLVM/convert-to-llvmir.mlir b/mlir/test/Conversion/StandardToLLVM/convert-to-llvmir.mlir
--- a/mlir/test/Conversion/StandardToLLVM/convert-to-llvmir.mlir
+++ b/mlir/test/Conversion/StandardToLLVM/convert-to-llvmir.mlir
@@ -1291,3 +1291,26 @@
 func @memref_index(%arg0: memref<32xindex>) -> memref<32xindex> {
   return %arg0 : memref<32xindex>
 }
+
+// -----
+
+// CHECK-LABEL: func @rank_of_unranked
+// CHECK32-LABEL: func @rank_of_unranked
+func @rank_of_unranked(%unranked: memref<*xi32>) {
+  %rank = rank %unranked : memref<*xi32>
+  return
+}
+// CHECK-NEXT: llvm.mlir.undef
+// CHECK-NEXT: llvm.insertvalue
+// CHECK-NEXT: llvm.insertvalue
+// CHECK-NEXT: llvm.extractvalue %{{.*}}[0] : !llvm<"{ i64, i8* }">
+// CHECK32: llvm.extractvalue %{{.*}}[0] : !llvm<"{ i64, i8* }">
+
+// CHECK-LABEL: func @rank_of_ranked
+// CHECK32-LABEL: func @rank_of_ranked
+func @rank_of_ranked(%ranked: memref<?xi32>) {
+  %rank = rank %ranked : memref<?xi32>
+  return
+}
+// CHECK: llvm.mlir.constant(1 : index) : !llvm.i64
+// CHECK32: llvm.mlir.constant(1 : index) : !llvm.i32