diff --git a/mlir/lib/Conversion/FuncToLLVM/FuncToLLVM.cpp b/mlir/lib/Conversion/FuncToLLVM/FuncToLLVM.cpp
--- a/mlir/lib/Conversion/FuncToLLVM/FuncToLLVM.cpp
+++ b/mlir/lib/Conversion/FuncToLLVM/FuncToLLVM.cpp
@@ -542,6 +542,16 @@
         return failure();
     }
 
+    if (useBarePtrCallConv) {
+      for (auto it : callOp->getOperands()) {
+        Type operandType = it.getType();
+        if (operandType.isa<UnrankedMemRefType>()) {
+          // Unranked memref is not supported in the bare pointer calling
+          // convention.
+          return failure();
+        }
+      }
+    }
     auto promoted = this->getTypeConverter()->promoteOperands(
         callOp.getLoc(), /*opOperands=*/callOp->getOperands(),
         adaptor.getOperands(), rewriter, useBarePtrCallConv);
diff --git a/mlir/test/Conversion/FuncToLLVM/func-memref-return.mlir b/mlir/test/Conversion/FuncToLLVM/func-memref-return.mlir
--- a/mlir/test/Conversion/FuncToLLVM/func-memref-return.mlir
+++ b/mlir/test/Conversion/FuncToLLVM/func-memref-return.mlir
@@ -103,3 +103,14 @@
 func.func @unconvertible_multiresult(%arg0: memref<?xf32> , %arg1: memref<?xf32>) -> (memref<?xf32>, memref<?xf32>) {
   return %arg0, %arg1 : memref<?xf32>, memref<?xf32>
 }
+
+// -----
+// BAREPTR-LABEL: func @unranked_memref(
+// BAREPTR-SAME: %{{.*}}: memref<*xi32>)
+func.func @unranked_memref(%arg0:memref<*xi32>) {
+  // BAREPTR:      call @printMemrefI32(%arg{{.*}}) : (memref<*xi32>) -> ()
+  // BAREPTR-NEXT: llvm.return
+  call @printMemrefI32(%arg0) : (memref<*xi32>) -> ()
+  return
+}
+func.func private @printMemrefI32(memref<*xi32>)