diff --git a/mlir/include/mlir/IR/BuiltinTypes.h b/mlir/include/mlir/IR/BuiltinTypes.h
--- a/mlir/include/mlir/IR/BuiltinTypes.h
+++ b/mlir/include/mlir/IR/BuiltinTypes.h
@@ -110,6 +110,10 @@
   /// size. Otherwise, abort.
   int64_t getNumDynamicDims() const;
 
+  /// If `dim` is a dynamic dim, return its relative index among the dynamic
+  /// dims. Otherwise, abort. The result is guaranteed to be nonnegative.
+  int64_t getRelativeIndexOfDynamicDim(unsigned dim) const;
+
   /// If this is ranked type, return the size of the specified dimension.
   /// Otherwise, abort.
   int64_t getDimSize(unsigned idx) const;
diff --git a/mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp b/mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp
--- a/mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp
+++ b/mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp
@@ -175,9 +175,9 @@
   LogicalResult matchAndRewrite(T alloc,
                                 PatternRewriter &rewriter) const override {
     if (llvm::any_of(alloc->getUsers(), [&](Operation *op) {
-        if (auto storeOp = dyn_cast<StoreOp>(op))
-          return storeOp.value() == alloc;
-        return !isa<DeallocOp>(op);
+          if (auto storeOp = dyn_cast<StoreOp>(op))
+            return storeOp.value() == alloc;
+          return !isa<DeallocOp>(op);
         }))
       return failure();
 
@@ -677,9 +677,9 @@
 
   if (auto sizeInterface =
           dyn_cast_or_null<OffsetSizeAndStrideOpInterface>(definingOp)) {
-    assert(sizeInterface.isDynamicSize(unsignedIndex) &&
-           "Expected dynamic subview size");
-    return sizeInterface.getDynamicSize(unsignedIndex);
+    int64_t nthDynamicIndex =
+        memrefType.getRelativeIndexOfDynamicDim(unsignedIndex);
+    return sizeInterface.sizes()[nthDynamicIndex];
   }
 
   // dim(memrefcast) -> dim
diff --git a/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp b/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp
--- a/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp
+++ b/mlir/lib/Dialect/Tensor/IR/TensorOps.cpp
@@ -271,13 +271,21 @@
     return Value{*dynExtents};
   }
 
+  // dim(insert_slice.result()) -> dim(insert_slice.dest())
+  if (auto insertSliceOp =
+          dyn_cast_or_null<tensor::InsertSliceOp>(definingOp)) {
+    this->sourceMutable().assign(insertSliceOp.dest());
+    return getResult();
+  }
+
   // The size at the given index is now known to be a dynamic size.
   unsigned unsignedIndex = index.getValue().getZExtValue();
 
-  if (auto sliceOp = dyn_cast_or_null<tensor::ExtractSliceOp>(definingOp)) {
-    assert(sliceOp.isDynamicSize(unsignedIndex) &&
-           "Expected dynamic slice size");
-    return sliceOp.getDynamicSize(unsignedIndex);
+  if (auto sizeInterface =
+          dyn_cast_or_null<OffsetSizeAndStrideOpInterface>(definingOp)) {
+    int64_t nthDynamicIndex =
+        tensorType.getRelativeIndexOfDynamicDim(unsignedIndex);
+    return sizeInterface.sizes()[nthDynamicIndex];
   }
 
   // dim(cast) -> dim
diff --git a/mlir/lib/IR/BuiltinTypes.cpp b/mlir/lib/IR/BuiltinTypes.cpp
--- a/mlir/lib/IR/BuiltinTypes.cpp
+++ b/mlir/lib/IR/BuiltinTypes.cpp
@@ -427,6 +427,15 @@
   return llvm::count_if(getShape(), isDynamic);
 }
 
+int64_t ShapedType::getRelativeIndexOfDynamicDim(unsigned dim) const {
+  assert(isDynamicDim(dim) && "expected a dynamic dim");
+  int nthDynamicIndex = -1;
+  for (unsigned idx = 0; idx <= dim; ++idx)
+    if (isDynamicDim(idx))
+      ++nthDynamicIndex;
+  return nthDynamicIndex;
+}
+
 bool ShapedType::hasStaticShape() const {
   return hasRank() && llvm::none_of(getShape(), isDynamic);
 }
diff --git a/mlir/test/Dialect/MemRef/canonicalize.mlir b/mlir/test/Dialect/MemRef/canonicalize.mlir
--- a/mlir/test/Dialect/MemRef/canonicalize.mlir
+++ b/mlir/test/Dialect/MemRef/canonicalize.mlir
@@ -387,11 +387,32 @@
 }
 
 // -----
+
 // CHECK-LABEL: func @allocator
 // CHECK:   %[[alloc:.+]] = memref.alloc
 // CHECK:   memref.store %[[alloc:.+]], %arg0
 func @allocator(%arg0 : memref<memref<?xi32>>, %arg1 : index)  {
   %0 = memref.alloc(%arg1) : memref<?xi32>
   memref.store %0, %arg0[] : memref<memref<?xi32>>
-  return 
+  return
+}
+
+// -----
+
+#map0 = affine_map<(d0, d1)[s0, s1, s2] -> (d0 * s1 + s0 + d1 * s2)>
+
+// CHECK-LABEL: func @rank_reducing_subview_dim
+//  CHECK-SAME:   %[[IDX_0:[0-9a-zA-Z]*]]: index
+//  CHECK-SAME:   %[[IDX_1:[0-9a-zA-Z]*]]: index
+func @rank_reducing_subview_dim(%arg0 : memref<?x?x?xf32>, %arg1 : index,
+    %arg2 : index) -> index
+{
+  %c0 = constant 0 : index
+  %c1 = constant 1 : index
+  %c4 = constant 4 : index
+  %0 = memref.subview %arg0[%c0, %arg1, %c1] [%c4, 1, %arg2] [%c1, %c1, %c1] : memref<?x?x?xf32> to memref<?x?xf32, #map0>
+  %1 = memref.dim %0, %c1 : memref<?x?xf32, #map0>
+
+  // CHECK-NEXT: return %[[IDX_1]] : index
+  return %1 : index
 }
diff --git a/mlir/test/Dialect/Tensor/canonicalize.mlir b/mlir/test/Dialect/Tensor/canonicalize.mlir
--- a/mlir/test/Dialect/Tensor/canonicalize.mlir
+++ b/mlir/test/Dialect/Tensor/canonicalize.mlir
@@ -517,3 +517,21 @@
   %2 = tensor.dim %0, %c1 : tensor<?x?xf32>
   return %1, %2: index, index
 }
+
+// -----
+
+// CHECK-LABEL: func @rank_reducing_subview_dim
+//  CHECK-SAME:   %[[IDX_0:[0-9a-zA-Z]*]]: index
+//  CHECK-SAME:   %[[IDX_1:[0-9a-zA-Z]*]]: index
+func @rank_reducing_subview_dim(%arg0 : tensor<?x?x?xf32>, %arg1 : index,
+    %arg2 : index) -> index
+{
+  %c0 = constant 0 : index
+  %c1 = constant 1 : index
+  %c4 = constant 4 : index
+  %0 = tensor.extract_slice %arg0[%c0, %arg1, %c1] [%c4, 1, %arg2] [%c1, %c1, %c1] : tensor<?x?x?xf32> to tensor<?x?xf32>
+  %1 = tensor.dim %0, %c1 : tensor<?x?xf32>
+
+  // CHECK-NEXT: return %[[IDX_1]] : index
+  return %1 : index
+}