diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -198,6 +198,7 @@
   __ranges/enable_borrowed_range.h
   __ranges/enable_view.h
   __ranges/iota_view.h
+  __ranges/lazy_split_view.h
   __ranges/non_propagating_cache.h
   __ranges/ref_view.h
   __ranges/single_view.h
diff --git a/libcxx/include/__ranges/lazy_split_view.h b/libcxx/include/__ranges/lazy_split_view.h
new file mode 100644
--- /dev/null
+++ b/libcxx/include/__ranges/lazy_split_view.h
@@ -0,0 +1,319 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+#ifndef _LIBCPP___RANGES_LAZY_SPLIT_VIEW_H
+#define _LIBCPP___RANGES_LAZY_SPLIT_VIEW_H
+
+#include <__config>
+#include <__iterator/concepts.h>
+#include <__iterator/incrementable_traits.h>
+#include <__iterator/iterator_traits.h>
+#include <__ranges/copyable_box.h>
+#include <__ranges/single_view.h>
+#include <__ranges/enable_borrowed_range.h>
+#include <__ranges/view_interface.h>
+#include <algorithm>
+#include <concepts>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if !defined(_LIBCPP_HAS_NO_RANGES)
+
+// REVIEW-NOTE: Will be its own patch. Not up for review.
+
+template<class _I1, class _I2, class _Range,
+         class _P1 = std::identity, class _P2 = std::identity>
+concept indirectly_comparable =
+    indirect_binary_predicate<_Range, projected<_I1, _P1>, projected<_I2, _P2>>;
+
+// END-REVIEW-NOTE
+
+namespace ranges {
+  template<auto> struct __require_constant;
+
+  template<class _Range>
+  concept __tiny_range =
+    sized_range<_Range> &&
+    requires { typename __require_constant<remove_reference_t<_Range>::size()>; } &&
+    (remove_reference_t<_Range>::size() <= 1);
+
+  template<input_range _View, forward_range _Pattern>
+    requires view<_View> && view<_Pattern> &&
+             indirectly_comparable<iterator_t<_View>, iterator_t<_Pattern>, ranges::equal_to> &&
+             (forward_range<_View> || __tiny_range<_Pattern>)
+  class lazy_split_view : public view_interface<lazy_split_view<_View, _Pattern>> {
+    template<bool> struct __inner_iterator;
+
+    // TODO: LWG issue: if there's no current iterator this is unimplementable as far as I can tell.
+    template<class>
+    struct __current_iter_base {};
+
+    template<forward_iterator _Iter>
+    struct __current_iter_base<_Iter> {
+        _Iter __current_ = _Iter();
+    };
+
+    template<bool _Const>
+    struct __outer_iterator
+      : public __current_iter_base<iterator_t<__maybe_const<_Const, _View>>> {
+
+    private:
+      using _Parent = __maybe_const<_Const, lazy_split_view>;
+      using _Base = __maybe_const<_Const, _View>;
+
+    public:
+      _Parent *__parent_ = nullptr;
+      bool __trailing_empty_ = false;
+
+      using iterator_concept = conditional_t<forward_range<_Base>, forward_iterator_tag, input_iterator_tag>;
+      using iterator_category = input_iterator_tag;
+      using difference_type = range_difference_t<_Base>;
+      struct value_type
+        : view_interface<value_type> {
+      private:
+        __outer_iterator __i_ = __outer_iterator();
+      public:
+        value_type() = default;
+        constexpr explicit value_type(__outer_iterator __i)
+          : __i_(_VSTD::move(__i)) {}
+
+        constexpr __inner_iterator<_Const> begin() const { return __inner_iterator<_Const>{__i_}; }
+        constexpr default_sentinel_t end() const { return default_sentinel; }
+      };
+
+      __outer_iterator() = default; // TODO: shouldn't this require that base iterator is default ctorable?
+
+      constexpr explicit __outer_iterator(_Parent& __parent)
+        requires (!forward_range<_Base>)
+        : __parent_(_VSTD::addressof(__parent)) {}
+
+      constexpr __outer_iterator(_Parent& __parent, iterator_t<_Base> __current)
+        requires forward_range<_Base>
+        : __parent_(_VSTD::addressof(__parent)), __current_(_VSTD::move(__current)) {}
+
+      constexpr __outer_iterator(__outer_iterator<!_Const> __i)
+        requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>>
+        : __parent_(__i.__parent_), __current_(_VSTD::move(__i.__current_)) {}
+
+      constexpr value_type operator*() const { return value_type{*this}; }
+
+      constexpr __outer_iterator& operator++() {
+        const auto __end = ranges::end(__parent_->__base_);
+        // LWG editorial: this should have a trailing underscore.
+        if (__current_ == __end) {
+          __trailing_empty_ = false;
+          return *this;
+        }
+
+        const auto __srange = ranges::subrange{__parent_->__pattern_};
+        const auto __pbegin = __srange.begin();
+        const auto __pend = __srange.end();
+
+        if (__pbegin == __pend) {
+          ++__current_;
+        } else if (__tiny_range<_Pattern>) {
+          __current_ = _VSTD::find(_VSTD::move(__current_), __end, *__pbegin);
+          if (__current_ != __end) {
+            ++__current_;
+            if (__current_ == __end)
+              __trailing_empty_ = true;
+          }
+        } else {
+          do {
+            const auto [__b, __p] = _VSTD::mismatch(__current_, __end, __pbegin, __pend);
+            if (__p == __pend) {
+              __current_ = __b;
+              if (__current_ == __end)
+                __trailing_empty_ = true;
+              break;
+            }
+          } while (++__current_ != __end);
+        }
+        return *this;
+      }
+
+      constexpr decltype(auto) operator++(int) {
+        if constexpr (forward_range<_Base>) {
+          auto __tmp = *this;
+          ++*this;
+          return __tmp;
+        }
+        ++*this;
+      }
+
+      friend constexpr bool operator==(const __outer_iterator& __x, const __outer_iterator& __y)
+        requires forward_range<_Base>
+      {
+        return __x.__current_ == __y.__current_ && __x.__trailing_empty_ == __y.__trailing_empty_;
+      }
+
+      friend constexpr bool operator==(const __outer_iterator& __x, default_sentinel_t) {
+        return __x.__current_ == ranges::end(__x.__parent_->__base_) && !__x.__trailing_empty_;
+      }
+    };
+
+    template<bool _Const> struct __inner_iterator {
+    private:
+      using _Base = __maybe_const<_Const, _View>;
+      __outer_iterator<_Const> __i_ = __outer_iterator<_Const>();
+      bool __incremented_ = false;
+
+    public:
+      using iterator_Concept = typename __outer_iterator<_Const>::iterator_concept;
+      using iterator_category = _If<
+        derived_from<typename iterator_traits<iterator_t<_Base>>::iterator_category, forward_iterator_tag>,
+        forward_iterator_tag,
+        typename iterator_traits<iterator_t<_Base>>::iterator_category
+      >;
+
+      using value_type = range_value_t<_Base>;
+      using difference_type = range_difference_t<_Base>;
+
+      __inner_iterator() = default;
+
+      constexpr explicit __inner_iterator(__outer_iterator<_Const> __i)
+        : __i_(_VSTD::move(__i)) {}
+
+      constexpr const iterator_t<_Base>& base() const& { return __i_.__current_; }
+      constexpr iterator_t<_Base> base() && { return _VSTD::move(__i_.__current_); }
+
+      constexpr decltype(auto) operator*() const { return *__i_.__current_; }
+
+      constexpr __inner_iterator& operator++() {
+        __incremented_ = true;
+
+        if constexpr (!forward_range<_Base>) {
+          if constexpr (_Pattern::size() == 0) {
+            return *this;
+          }
+        }
+
+        ++__i_.__current_;
+        return *this;
+      }
+      constexpr decltype(auto) operator++(int) {
+        if constexpr (forward_range<_Base>) {
+          auto __tmp = *this;
+          ++*this;
+          return __tmp;
+        }
+
+        ++*this;
+      }
+
+      friend constexpr bool operator==(const __inner_iterator& __x, const __inner_iterator& __y)
+        requires forward_range<_Base>
+      {
+        return __x.__i_.__current_ == __y.__i_.__current_;
+      }
+
+      friend constexpr bool operator==(const __inner_iterator& __x, default_sentinel_t) {
+        const auto __srange = ranges::subrange{__x.__i_.__parent_->__pattern_};
+              auto __pcur = __srange.begin();
+        const auto __pend = __srange.end();
+        const auto __end = ranges::end(__x.__i_.__parent_->__base_);
+
+        auto __cur = __x.__i_.__current_;
+        if (__cur == __end) return true;
+        if (__pcur == __pend)  return __x.__incremented_;
+
+        if constexpr (__tiny_range<_Pattern>) {
+          return *__cur == *__pcur;
+        }
+
+        do {
+          if (*__cur != *__pcur) return false;
+          if (++__pcur == __pend) return true;
+        } while (++__cur != __end);
+
+        return false; // TODO: shouldn't this be true?
+      }
+
+      friend constexpr decltype(auto) iter_move(const __inner_iterator& __i)
+        noexcept(noexcept(ranges::iter_move(__i.__i_.__current_)))
+      {
+        return ranges::iter_move(__i.__i_.__current_);
+      }
+
+      friend constexpr void iter_swap(const __inner_iterator& __x, const __inner_iterator& __y)
+        noexcept(noexcept(ranges::iter_swap(__x.__i_.__current_, __y.__i_.__current_)))
+        requires indirectly_swappable<iterator_t<_Base>>
+      {
+        ranges::iter_swap(__x.__i_.__current_, __y.__i_.__current_);
+      }
+    };
+
+  public:
+    _View __base_ = _View();
+    _Pattern __pattern_ = _Pattern();
+    __non_propagating_cache<iterator_t<_View>> __current_; // TODO: only if not forward_range.
+
+    lazy_split_view()
+      requires default_initializable<_View> && default_initializable<_Pattern> = default;
+
+    constexpr lazy_split_view(_View __base, _Pattern __pattern)
+      : __base_(_VSTD::move(__base)), __pattern_(_VSTD::move(__pattern)) {}
+
+    template<input_range _Range>
+      requires constructible_from<_View, views::all_t<_Range>> &&
+               constructible_from<_Pattern, single_view<range_value_t<_Range>>>
+    constexpr lazy_split_view(_Range&& __r, range_value_t<_Range> __e)
+      : __base_(views::all(_VSTD::forward<_Range>(__r)))
+      , __pattern_(ranges::single_view(_VSTD::move(__e))) {}
+
+    constexpr _View base() const& requires copy_constructible<_View> { return __base_; }
+    constexpr _View base() && { return _VSTD::move(__base_); }
+
+    constexpr auto begin() {
+      if constexpr (forward_range<_View>)
+        return __outer_iterator<__simple_view<_View>>{*this, ranges::begin(__base_)};
+      else {
+        __current_.__set(ranges::begin(__base_));
+        return __outer_iterator<false>{*this};
+      }
+    }
+
+    constexpr auto begin() const requires forward_range<_View> && forward_range<const _View> {
+      return __outer_iterator<true>{*this, ranges::begin(__base_)};
+    }
+
+    constexpr auto end() requires forward_range<_View> && common_range<_View> {
+      return __outer_iterator<__simple_view<_View>>{*this, ranges::end(__base_)};
+    }
+
+    constexpr auto end() const {
+      if constexpr (forward_range<_View> && forward_range<const _View> && common_range<const _View>) {
+        return __outer_iterator<true>{*this, ranges::end(__base_)};
+      }
+      return default_sentinel;
+    }
+  };
+
+  template<class _Range, class _Pattern>
+  lazy_split_view(_Range&&, _Pattern&&) -> lazy_split_view<views::all_t<_Range>, views::all_t<_Pattern>>;
+
+  template<input_range _Range>
+  lazy_split_view(_Range&&, range_value_t<_Range>)
+    -> lazy_split_view<views::all_t<_Range>, single_view<range_value_t<_Range>>>;
+} // namespace ranges
+
+#endif // !defined(_LIBCPP_HAS_NO_RANGES)
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___RANGES_LAZY_SPLIT_VIEW_H
diff --git a/libcxx/include/ranges b/libcxx/include/ranges
--- a/libcxx/include/ranges
+++ b/libcxx/include/ranges
@@ -195,6 +195,7 @@
 #include <__ranges/enable_borrowed_range.h>
 #include <__ranges/enable_view.h>
 #include <__ranges/iota_view.h>
+#include <__ranges/lazy_split_view.h>
 #include <__ranges/ref_view.h>
 #include <__ranges/single_view.h>
 #include <__ranges/size.h>