diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -267,7 +267,7 @@
   return adl_begin(RangeOrContainer) == adl_end(RangeOrContainer);
 }
 
-/// Returns true of the given range only contains a single element.
+/// Returns true if the given container only contains a single element.
 template <typename ContainerTy> bool hasSingleElement(ContainerTy &&c) {
   auto it = std::begin(c), e = std::end(c);
   return it != e && std::next(it) == e;
@@ -1924,7 +1924,7 @@
 
 /// Return true if the sequence [Begin, End) has N or more items. Runs in O(N)
 /// time. Not meant for use with random-access iterators.
-/// Can optionally take a predicate to filter lazily some items.
+/// Can optionally take a predicate to lazily filter some items.
 template<typename IterTy,
          typename Pred = bool (*)(const decltype(*std::declval<IterTy>()) &)>
 bool hasNItemsOrMore(
@@ -1944,6 +1944,36 @@
   return true;
 }
 
+/// Returns true if the sequence [Begin, End) has N or less items. Can
+/// optionally take a predicate to lazily filter some items
+template <typename IterTy,
+          typename Pred = bool (*)(const decltype(*std::declval<IterTy>()) &)>
+bool hasNItemsOrLess(
+    IterTy &&Begin, IterTy &&End, unsigned N,
+    Pred &&ShouldBeCounted = [](const decltype(*std::declval<IterTy>()) &) {
+      return true;
+    }) {
+  assert(N != std::numeric_limits<unsigned>::max());
+  return !hasNItemsOrMore(Begin, End, N + 1, ShouldBeCounted);
+}
+
+/// Returns true if the given container has exactly N items
+template <typename ContainerTy> bool hasNItems(ContainerTy &&c, unsigned N) {
+  return hasNItems(std::begin(c), std::end(c), N);
+}
+
+/// Returns true if the given container has N or more items
+template <typename ContainerTy>
+bool hasNItemsOrMore(ContainerTy &&c, unsigned N) {
+  return hasNItemsOrMore(std::begin(c), std::end(c), N);
+}
+
+/// Returns true if the given container has N or less items
+template <typename ContainerTy>
+bool hasNItemsOrLess(ContainerTy &&c, unsigned N) {
+  return hasNItemsOrLess(std::begin(c), std::end(c), N);
+}
+
 /// Returns a raw pointer that represents the same address as the argument.
 ///
 /// This implementation can be removed once we move to C++20 where it's defined
diff --git a/mlir/include/mlir/IR/OpBase.td b/mlir/include/mlir/IR/OpBase.td
--- a/mlir/include/mlir/IR/OpBase.td
+++ b/mlir/include/mlir/IR/OpBase.td
@@ -1586,7 +1586,7 @@
 
 // A region with the given number of blocks.
 class SizedRegion<int numBlocks> : Region<
-  CPred<"$_self.getBlocks().size() == " # numBlocks>,
+  CPred<"llvm::hasNItems($_self, " # numBlocks # ")">,
   "region with " # numBlocks # " blocks">;
 
 // A variadic region constraint. It expands to zero or more of the base region.