diff --git a/CMake/AbseilDll.cmake b/CMake/AbseilDll.cmake
index 8b664c2..68e28c2 100644
--- a/CMake/AbseilDll.cmake
+++ b/CMake/AbseilDll.cmake
@@ -193,6 +193,7 @@
   "strings/escaping.cc"
   "strings/escaping.h"
   "strings/internal/cord_internal.h"
+  "strings/internal/cord_rep_flat.h"
   "strings/internal/charconv_bigint.cc"
   "strings/internal/charconv_bigint.h"
   "strings/internal/charconv_parse.cc"
diff --git a/README.chromium b/README.chromium
index ea67be2..7a5dbe5 100644
--- a/README.chromium
+++ b/README.chromium
@@ -4,7 +4,7 @@
 License: Apache 2.0
 License File: LICENSE
 Version: 0
-Revision: 5d8fc9192245f0ea67094af57399d7931d6bd53f
+Revision: 592924480acf034aec0454160492a20bccdbdf3e
 Security Critical: yes
 
 Description:
diff --git a/absl/base/call_once.h b/absl/base/call_once.h
index 5b468af..96109f5 100644
--- a/absl/base/call_once.h
+++ b/absl/base/call_once.h
@@ -177,15 +177,8 @@
                                   scheduling_mode) == kOnceInit) {
     base_internal::invoke(std::forward<Callable>(fn),
                           std::forward<Args>(args)...);
-    // The call to SpinLockWake below is an optimization, because the waiter
-    // in SpinLockWait is waiting with a short timeout. The atomic load/store
-    // sequence is slightly faster than an atomic exchange:
-    //   old_control = control->exchange(base_internal::kOnceDone,
-    //                                   std::memory_order_release);
-    // We opt for a slightly faster case when there are no waiters, in spite
-    // of longer tail latency when there are waiters.
-    old_control = control->load(std::memory_order_relaxed);
-    control->store(base_internal::kOnceDone, std::memory_order_release);
+    old_control =
+        control->exchange(base_internal::kOnceDone, std::memory_order_release);
     if (old_control == base_internal::kOnceWaiter) {
       base_internal::SpinLockWake(control, true);
     }
diff --git a/absl/base/internal/spinlock.h b/absl/base/internal/spinlock.h
index e6ac9e6..dce1c85 100644
--- a/absl/base/internal/spinlock.h
+++ b/absl/base/internal/spinlock.h
@@ -15,11 +15,8 @@
 //
 
 //  Most users requiring mutual exclusion should use Mutex.
-//  SpinLock is provided for use in three situations:
+//  SpinLock is provided for use in two situations:
 //   - for use in code that Mutex itself depends on
-//   - to get a faster fast-path release under low contention (without an
-//     atomic read-modify-write) In return, SpinLock has worse behaviour under
-//     contention, which is why Mutex is preferred in most situations.
 //   - for async signal safety (see below)
 
 // SpinLock is async signal safe.  If a spinlock is used within a signal
diff --git a/absl/base/internal/spinlock_wait.h b/absl/base/internal/spinlock_wait.h
index 169bc74..c34ce41 100644
--- a/absl/base/internal/spinlock_wait.h
+++ b/absl/base/internal/spinlock_wait.h
@@ -43,18 +43,16 @@
                       const SpinLockWaitTransition trans[],
                       SchedulingMode scheduling_mode);
 
-// If possible, wake some thread that has called SpinLockDelay(w, ...). If
-// "all" is true, wake all such threads.  This call is a hint, and on some
-// systems it may be a no-op; threads calling SpinLockDelay() will always wake
-// eventually even if SpinLockWake() is never called.
+// If possible, wake some thread that has called SpinLockDelay(w, ...). If `all`
+// is true, wake all such threads. On some systems, this may be a no-op; on
+// those systems, threads calling SpinLockDelay() will always wake eventually
+// even if SpinLockWake() is never called.
 void SpinLockWake(std::atomic<uint32_t> *w, bool all);
 
 // Wait for an appropriate spin delay on iteration "loop" of a
 // spin loop on location *w, whose previously observed value was "value".
 // SpinLockDelay() may do nothing, may yield the CPU, may sleep a clock tick,
-// or may wait for a delay that can be truncated by a call to SpinLockWake(w).
-// In all cases, it must return in bounded time even if SpinLockWake() is not
-// called.
+// or may wait for a call to SpinLockWake(w).
 void SpinLockDelay(std::atomic<uint32_t> *w, uint32_t value, int loop,
                    base_internal::SchedulingMode scheduling_mode);
 
diff --git a/absl/flags/internal/commandlineflag.h b/absl/flags/internal/commandlineflag.h
index cb46fe2..ebfe81b 100644
--- a/absl/flags/internal/commandlineflag.h
+++ b/absl/flags/internal/commandlineflag.h
@@ -24,7 +24,7 @@
 namespace flags_internal {
 
 // An alias for flag fast type id. This value identifies the flag value type
-// simialarly to typeid(T), without relying on RTTI being available. In most
+// similarly to typeid(T), without relying on RTTI being available. In most
 // cases this id is enough to uniquely identify the flag's value type. In a few
 // cases we'll have to resort to using actual RTTI implementation if it is
 // available.
diff --git a/absl/status/status.h b/absl/status/status.h
index c4d6fce..9019e6c 100644
--- a/absl/status/status.h
+++ b/absl/status/status.h
@@ -57,6 +57,7 @@
 #include "absl/container/inlined_vector.h"
 #include "absl/status/internal/status_internal.h"
 #include "absl/strings/cord.h"
+#include "absl/strings/string_view.h"
 #include "absl/types/optional.h"
 
 namespace absl {
diff --git a/absl/strings/BUILD.bazel b/absl/strings/BUILD.bazel
index 30a8dd2..a1579a4 100644
--- a/absl/strings/BUILD.bazel
+++ b/absl/strings/BUILD.bazel
@@ -267,7 +267,10 @@
 
 cc_library(
     name = "cord_internal",
-    hdrs = ["internal/cord_internal.h"],
+    hdrs = [
+        "internal/cord_internal.h",
+        "internal/cord_rep_flat.h",
+    ],
     copts = ABSL_DEFAULT_COPTS,
     visibility = ["//visibility:private"],
     deps = [
diff --git a/absl/strings/BUILD.gn b/absl/strings/BUILD.gn
index 4495790..a949c9d 100644
--- a/absl/strings/BUILD.gn
+++ b/absl/strings/BUILD.gn
@@ -117,7 +117,10 @@
 }
 
 absl_source_set("cord_internal") {
-  public = [ "internal/cord_internal.h" ]
+  public = [
+    "internal/cord_internal.h",
+    "internal/cord_rep_flat.h",
+  ]
   visibility = [ ":*" ]
   deps = [
     ":strings",
diff --git a/absl/strings/CMakeLists.txt b/absl/strings/CMakeLists.txt
index 2b994a7..af0b57d 100644
--- a/absl/strings/CMakeLists.txt
+++ b/absl/strings/CMakeLists.txt
@@ -557,6 +557,7 @@
   SRCS
     "cord.cc"
     "internal/cord_internal.h"
+    "internal/cord_rep_flat.h"
   COPTS
     ${ABSL_DEFAULT_COPTS}
   DEPS
diff --git a/absl/strings/cord.cc b/absl/strings/cord.cc
index ec1e970..7c4f6c9 100644
--- a/absl/strings/cord.cc
+++ b/absl/strings/cord.cc
@@ -36,6 +36,7 @@
 #include "absl/container/inlined_vector.h"
 #include "absl/strings/escaping.h"
 #include "absl/strings/internal/cord_internal.h"
+#include "absl/strings/internal/cord_rep_flat.h"
 #include "absl/strings/internal/resize_uninitialized.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
@@ -48,8 +49,12 @@
 using ::absl::cord_internal::CordRep;
 using ::absl::cord_internal::CordRepConcat;
 using ::absl::cord_internal::CordRepExternal;
+using ::absl::cord_internal::CordRepFlat;
 using ::absl::cord_internal::CordRepSubstring;
 
+using ::absl::cord_internal::kMinFlatLength;
+using ::absl::cord_internal::kMaxFlatLength;
+
 using ::absl::cord_internal::CONCAT;
 using ::absl::cord_internal::EXTERNAL;
 using ::absl::cord_internal::FLAT;
@@ -90,64 +95,9 @@
 
 }  // namespace cord_internal
 
-static const size_t kFlatOverhead = offsetof(CordRep, data);
-
-// Largest and smallest flat node lengths we are willing to allocate
-// Flat allocation size is stored in tag, which currently can encode sizes up
-// to 4K, encoded as multiple of either 8 or 32 bytes.
-// If we allow for larger sizes, we need to change this to 8/64, 16/128, etc.
-// kMinFlatSize is bounded by tag needing to be at least FLAT * 8 bytes, and
-// ideally a 'nice' size aligning with allocation and cacheline sizes like 32.
-// kMaxFlatSize is bounded by the size resulting in a computed tag no greater
-// than MAX_FLAT_TAG. MAX_FLAT_TAG provides for additional 'high' tag values.
-static constexpr size_t kMinFlatSize = 32;
-static constexpr size_t kMaxFlatSize = 4096;
-static constexpr size_t kMaxFlatLength = kMaxFlatSize - kFlatOverhead;
-static constexpr size_t kMinFlatLength = kMinFlatSize - kFlatOverhead;
-
-static constexpr size_t AllocatedSizeToTagUnchecked(size_t size) {
-  return (size <= 1024) ? size / 8 : 128 + size / 32 - 1024 / 32;
-}
-
-static_assert(kMinFlatSize / 8 >= FLAT, "");
-static_assert(AllocatedSizeToTagUnchecked(kMaxFlatSize) <= MAX_FLAT_TAG, "");
-
 // Prefer copying blocks of at most this size, otherwise reference count.
 static const size_t kMaxBytesToCopy = 511;
 
-// Helper functions for rounded div, and rounding to exact sizes.
-static size_t DivUp(size_t n, size_t m) { return (n + m - 1) / m; }
-static size_t RoundUp(size_t n, size_t m) { return DivUp(n, m) * m; }
-
-// Returns the size to the nearest equal or larger value that can be
-// expressed exactly as a tag value.
-static size_t RoundUpForTag(size_t size) {
-  return RoundUp(size, (size <= 1024) ? 8 : 32);
-}
-
-// Converts the allocated size to a tag, rounding down if the size
-// does not exactly match a 'tag expressible' size value. The result is
-// undefined if the size exceeds the maximum size that can be encoded in
-// a tag, i.e., if size is larger than TagToAllocatedSize(<max tag>).
-static uint8_t AllocatedSizeToTag(size_t size) {
-  const size_t tag = AllocatedSizeToTagUnchecked(size);
-  assert(tag <= std::numeric_limits<uint8_t>::max());
-  return tag;
-}
-
-// Converts the provided tag to the corresponding allocated size
-static constexpr size_t TagToAllocatedSize(uint8_t tag) {
-  return (tag <= 128) ? (tag * 8) : (1024 + (tag - 128) * 32);
-}
-
-// Converts the provided tag to the corresponding available data length
-static constexpr size_t TagToLength(uint8_t tag) {
-  return TagToAllocatedSize(tag) - kFlatOverhead;
-}
-
-// Enforce that kMaxFlatSize maps to a well-known exact tag value.
-static_assert(TagToAllocatedSize(224) == kMaxFlatSize, "Bad tag logic");
-
 constexpr uint64_t Fibonacci(unsigned char n, uint64_t a = 0, uint64_t b = 1) {
   return n == 0 ? a : Fibonacci(n - 1, b, a + b);
 }
@@ -269,9 +219,7 @@
         continue;
       }
     } else if (rep->tag == EXTERNAL) {
-      CordRepExternal* rep_external = rep->external();
-      assert(rep_external->releaser_invoker != nullptr);
-      rep_external->releaser_invoker(rep_external);
+      CordRepExternal::Delete(rep);
       rep = nullptr;
     } else if (rep->tag == SUBSTRING) {
       CordRepSubstring* rep_substring = rep->substring();
@@ -283,17 +231,7 @@
         continue;
       }
     } else {
-      // Flat CordReps are allocated and constructed with raw ::operator new
-      // and placement new, and must be destructed and deallocated
-      // accordingly.
-#if defined(__cpp_sized_deallocation)
-      size_t size = TagToAllocatedSize(rep->tag);
-      rep->~CordRep();
-      ::operator delete(rep, size);
-#else
-      rep->~CordRep();
-      ::operator delete(rep);
-#endif
+      CordRepFlat::Delete(rep);
       rep = nullptr;
     }
 
@@ -383,22 +321,6 @@
   return reps[0];
 }
 
-// Create a new flat node.
-static CordRep* NewFlat(size_t length_hint) {
-  if (length_hint <= kMinFlatLength) {
-    length_hint = kMinFlatLength;
-  } else if (length_hint > kMaxFlatLength) {
-    length_hint = kMaxFlatLength;
-  }
-
-  // Round size up so it matches a size we can exactly express in a tag.
-  const size_t size = RoundUpForTag(length_hint + kFlatOverhead);
-  void* const raw_rep = ::operator new(size);
-  CordRep* rep = new (raw_rep) CordRep();
-  rep->tag = AllocatedSizeToTag(size);
-  return VerifyTree(rep);
-}
-
 // Create a new tree out of the specified array.
 // The returned node has a refcount of 1.
 static CordRep* NewTree(const char* data,
@@ -409,7 +331,7 @@
   size_t n = 0;
   do {
     const size_t len = std::min(length, kMaxFlatLength);
-    CordRep* rep = NewFlat(len + alloc_hint);
+    CordRep* rep = CordRepFlat::New(len + alloc_hint);
     rep->length = len;
     memcpy(rep->data, data, len);
     reps[n++] = VerifyTree(rep);
@@ -473,7 +395,7 @@
     return data_.as_tree.rep;
   }
 
-  CordRep* result = NewFlat(len + extra_hint);
+  CordRep* result = CordRepFlat::New(len + extra_hint);
   result->length = len;
   static_assert(kMinFlatLength >= sizeof(data_.as_chars), "");
   memcpy(result->data, data_.as_chars, sizeof(data_.as_chars));
@@ -535,7 +457,7 @@
   }
 
   const size_t in_use = dst->length;
-  const size_t capacity = TagToLength(dst->tag);
+  const size_t capacity = static_cast<CordRepFlat*>(dst)->Capacity();
   if (in_use == capacity) {
     *region = nullptr;
     *size = 0;
@@ -579,10 +501,9 @@
   }
 
   // Allocate new node.
-  CordRep* new_node =
-      NewFlat(std::max(static_cast<size_t>(root->length), max_length));
-  new_node->length =
-      std::min(static_cast<size_t>(TagToLength(new_node->tag)), max_length);
+  CordRepFlat* new_node =
+      CordRepFlat::New(std::max(static_cast<size_t>(root->length), max_length));
+  new_node->length = std::min(new_node->Capacity(), max_length);
   *region = new_node->data;
   *size = new_node->length;
   replace_tree(Concat(root, new_node));
@@ -607,8 +528,8 @@
   }
 
   // Allocate new node.
-  CordRep* new_node = NewFlat(root->length);
-  new_node->length = TagToLength(new_node->tag);
+  CordRepFlat* new_node = CordRepFlat::New(root->length);
+  new_node->length = new_node->Capacity();
   *region = new_node->data;
   *size = new_node->length;
   replace_tree(Concat(root, new_node));
@@ -618,7 +539,7 @@
 // will return true.
 static bool RepMemoryUsageLeaf(const CordRep* rep, size_t* total_mem_usage) {
   if (rep->tag >= FLAT) {
-    *total_mem_usage += TagToAllocatedSize(rep->tag);
+    *total_mem_usage += static_cast<const CordRepFlat*>(rep)->AllocatedSize();
     return true;
   }
   if (rep->tag == EXTERNAL) {
@@ -716,7 +637,8 @@
     return *this;
   }
   if (tree != nullptr && tree->tag >= FLAT &&
-      TagToLength(tree->tag) >= length && tree->refcount.IsOne()) {
+      static_cast<CordRepFlat*>(tree)->Capacity() >= length &&
+      tree->refcount.IsOne()) {
     // Copy in place if the existing FLAT node is reusable.
     memmove(tree->data, data, length);
     tree->length = length;
@@ -770,8 +692,9 @@
     // either double the inlined size, or the added size + 10%.
     const size_t size1 = inline_length * 2 + src_size;
     const size_t size2 = inline_length + src_size / 10;
-    root = NewFlat(std::max<size_t>(size1, size2));
-    appended = std::min(src_size, TagToLength(root->tag) - inline_length);
+    root = CordRepFlat::New(std::max<size_t>(size1, size2));
+    appended = std::min(
+        src_size, static_cast<CordRepFlat*>(root)->Capacity() - inline_length);
     memcpy(root->data, data_.as_chars, inline_length);
     memcpy(root->data + inline_length, src_data, appended);
     root->length = inline_length + appended;
@@ -1747,7 +1670,7 @@
   // Try to put the contents into a new flat rep. If they won't fit in the
   // biggest possible flat node, use an external rep instead.
   if (total_size <= kMaxFlatLength) {
-    new_rep = NewFlat(total_size);
+    new_rep = CordRepFlat::New(total_size);
     new_rep->length = total_size;
     new_buffer = new_rep->data;
     CopyToArraySlowPath(new_buffer);
@@ -1862,7 +1785,8 @@
           *os << absl::CEscape(std::string(rep->external()->base, rep->length));
         *os << "]\n";
       } else {
-        *os << "FLAT cap=" << TagToLength(rep->tag) << " [";
+        *os << "FLAT cap=" << static_cast<CordRepFlat*>(rep)->Capacity()
+            << " [";
         if (include_data)
           *os << absl::CEscape(std::string(rep->data, rep->length));
         *os << "]\n";
@@ -1910,8 +1834,9 @@
         worklist.push_back(node->concat()->left);
       }
     } else if (node->tag >= FLAT) {
-      ABSL_INTERNAL_CHECK(node->length <= TagToLength(node->tag),
-                          ReportError(root, node));
+      ABSL_INTERNAL_CHECK(
+          node->length <= static_cast<CordRepFlat*>(node)->Capacity(),
+          ReportError(root, node));
     } else if (node->tag == EXTERNAL) {
       ABSL_INTERNAL_CHECK(node->external()->base != nullptr,
                           ReportError(root, node));
@@ -1987,14 +1912,14 @@
 }
 
 namespace strings_internal {
-size_t CordTestAccess::FlatOverhead() { return kFlatOverhead; }
-size_t CordTestAccess::MaxFlatLength() { return kMaxFlatLength; }
+size_t CordTestAccess::FlatOverhead() { return cord_internal::kFlatOverhead; }
+size_t CordTestAccess::MaxFlatLength() { return cord_internal::kMaxFlatLength; }
 size_t CordTestAccess::FlatTagToLength(uint8_t tag) {
-  return TagToLength(tag);
+  return cord_internal::TagToLength(tag);
 }
 uint8_t CordTestAccess::LengthToTag(size_t s) {
   ABSL_INTERNAL_CHECK(s <= kMaxFlatLength, absl::StrCat("Invalid length ", s));
-  return AllocatedSizeToTag(s + kFlatOverhead);
+  return cord_internal::AllocatedSizeToTag(s + cord_internal::kFlatOverhead);
 }
 size_t CordTestAccess::SizeofCordRepConcat() { return sizeof(CordRepConcat); }
 size_t CordTestAccess::SizeofCordRepExternal() {
diff --git a/absl/strings/internal/cord_internal.h b/absl/strings/internal/cord_internal.h
index 195a798..ec2c767 100644
--- a/absl/strings/internal/cord_internal.h
+++ b/absl/strings/internal/cord_internal.h
@@ -108,8 +108,9 @@
 // functions in the base class.
 
 struct CordRepConcat;
-struct CordRepSubstring;
 struct CordRepExternal;
+struct CordRepFlat;
+struct CordRepSubstring;
 
 // Various representations that we allow
 enum CordRepKind {
@@ -180,6 +181,10 @@
   const char* base;
   // Pointer to function that knows how to call and destroy the releaser.
   ExternalReleaserInvoker releaser_invoker;
+
+  // Deletes (releases) the external rep.
+  // Requires rep != nullptr and rep->tag == EXTERNAL
+  static void Delete(CordRep* rep);
 };
 
 struct Rank1 {};
@@ -220,6 +225,13 @@
   }
 };
 
+inline void CordRepExternal::Delete(CordRep* rep) {
+  assert(rep != nullptr && rep->tag == EXTERNAL);
+  auto* rep_external = static_cast<CordRepExternal*>(rep);
+  assert(rep_external->releaser_invoker != nullptr);
+  rep_external->releaser_invoker(rep_external);
+}
+
 template <typename Str>
 struct ConstInitExternalStorage {
   ABSL_CONST_INIT static CordRepExternal value;
diff --git a/absl/strings/internal/cord_rep_flat.h b/absl/strings/internal/cord_rep_flat.h
new file mode 100644
index 0000000..3e2cd33
--- /dev/null
+++ b/absl/strings/internal/cord_rep_flat.h
@@ -0,0 +1,129 @@
+// Copyright 2020 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_STRINGS_INTERNAL_CORD_REP_FLAT_H_
+#define ABSL_STRINGS_INTERNAL_CORD_REP_FLAT_H_
+
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+
+#include "absl/strings/internal/cord_internal.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace cord_internal {
+
+// Note: all constants below are never ODR used and internal to cord, we define
+// these as static constexpr to avoid 'in struct' definition and usage clutter.
+
+// Largest and smallest flat node lengths we are willing to allocate
+// Flat allocation size is stored in tag, which currently can encode sizes up
+// to 4K, encoded as multiple of either 8 or 32 bytes.
+// If we allow for larger sizes, we need to change this to 8/64, 16/128, etc.
+// kMinFlatSize is bounded by tag needing to be at least FLAT * 8 bytes, and
+// ideally a 'nice' size aligning with allocation and cacheline sizes like 32.
+// kMaxFlatSize is bounded by the size resulting in a computed tag no greater
+// than MAX_FLAT_TAG. MAX_FLAT_TAG provides for additional 'high' tag values.
+static constexpr size_t kFlatOverhead = offsetof(CordRep, data);
+static constexpr size_t kMinFlatSize = 32;
+static constexpr size_t kMaxFlatSize = 4096;
+static constexpr size_t kMaxFlatLength = kMaxFlatSize - kFlatOverhead;
+static constexpr size_t kMinFlatLength = kMinFlatSize - kFlatOverhead;
+
+static constexpr size_t AllocatedSizeToTagUnchecked(size_t size) {
+  return (size <= 1024) ? size / 8 : 128 + size / 32 - 1024 / 32;
+}
+
+static_assert(kMinFlatSize / 8 >= FLAT, "");
+static_assert(AllocatedSizeToTagUnchecked(kMaxFlatSize) <= MAX_FLAT_TAG, "");
+
+// Helper functions for rounded div, and rounding to exact sizes.
+static size_t DivUp(size_t n, size_t m) { return (n + m - 1) / m; }
+static size_t RoundUp(size_t n, size_t m) { return DivUp(n, m) * m; }
+
+// Returns the size to the nearest equal or larger value that can be
+// expressed exactly as a tag value.
+static size_t RoundUpForTag(size_t size) {
+  return RoundUp(size, (size <= 1024) ? 8 : 32);
+}
+
+// Converts the allocated size to a tag, rounding down if the size
+// does not exactly match a 'tag expressible' size value. The result is
+// undefined if the size exceeds the maximum size that can be encoded in
+// a tag, i.e., if size is larger than TagToAllocatedSize(<max tag>).
+static uint8_t AllocatedSizeToTag(size_t size) {
+  const size_t tag = AllocatedSizeToTagUnchecked(size);
+  assert(tag <= MAX_FLAT_TAG);
+  return tag;
+}
+
+// Converts the provided tag to the corresponding allocated size
+static constexpr size_t TagToAllocatedSize(uint8_t tag) {
+  return (tag <= 128) ? (tag * 8) : (1024 + (tag - 128) * 32);
+}
+
+// Converts the provided tag to the corresponding available data length
+static constexpr size_t TagToLength(uint8_t tag) {
+  return TagToAllocatedSize(tag) - kFlatOverhead;
+}
+
+// Enforce that kMaxFlatSize maps to a well-known exact tag value.
+static_assert(TagToAllocatedSize(224) == kMaxFlatSize, "Bad tag logic");
+
+struct CordRepFlat : public CordRep {
+  // Creates a new flat node.
+  static CordRepFlat* New(size_t len) {
+    if (len <= kMinFlatLength) {
+      len = kMinFlatLength;
+    } else if (len > kMaxFlatLength) {
+      len = kMaxFlatLength;
+    }
+
+    // Round size up so it matches a size we can exactly express in a tag.
+    const size_t size = RoundUpForTag(len + kFlatOverhead);
+    void* const raw_rep = ::operator new(size);
+    CordRepFlat* rep = new (raw_rep) CordRepFlat();
+    rep->tag = AllocatedSizeToTag(size);
+    return rep;
+  }
+
+  // Deletes a CordRepFlat instance created previously through a call to New().
+  // Flat CordReps are allocated and constructed with raw ::operator new and
+  // placement new, and must be destructed and deallocated accordingly.
+  static void Delete(CordRep*rep) {
+    assert(rep->tag >= FLAT);
+#if defined(__cpp_sized_deallocation)
+    size_t size = TagToAllocatedSize(rep->tag);
+    rep->~CordRep();
+    ::operator delete(rep, size);
+#else
+    rep->~CordRep();
+    ::operator delete(rep);
+#endif
+  }
+
+  // Returns the maximum capacity (payload size) of this instance.
+  size_t Capacity() const { return TagToLength(tag); }
+
+  // Returns the allocated size (payload + overhead) of this instance.
+  size_t AllocatedSize() const { return TagToAllocatedSize(tag); }
+};
+
+}  // namespace cord_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STRINGS_INTERNAL_CORD_REP_FLAT_H_
diff --git a/symbols_arm64_dbg.def b/symbols_arm64_dbg.def
index dc7fd26..71e94c6 100644
--- a/symbols_arm64_dbg.def
+++ b/symbols_arm64_dbg.def
@@ -934,6 +934,7 @@
     ??0CordRep@cord_internal@absl@@QEAA@XZ
     ??0CordRepConcat@cord_internal@absl@@QEAA@XZ
     ??0CordRepExternal@cord_internal@absl@@QEAA@XZ
+    ??0CordRepFlat@cord_internal@absl@@QEAA@XZ
     ??0CordRepSubstring@cord_internal@absl@@QEAA@XZ
     ??0Duration@absl@@AEAA@_JI@Z
     ??0Duration@absl@@QEAA@XZ
@@ -1410,6 +1411,7 @@
     ?Allocate@?$AllocationTransaction@V?$allocator@PEBUCordRep@cord_internal@absl@@@__1@std@@@inlined_vector_internal@absl@@QEAAPEAPEBUCordRep@cord_internal@3@_K@Z
     ?Allocate@?$AllocationTransaction@V?$allocator@UPayload@status_internal@absl@@@__1@std@@@inlined_vector_internal@absl@@QEAAPEAUPayload@status_internal@3@_K@Z
     ?Allocate@?$AllocationTransaction@V?$allocator@USubRange@absl@@@__1@std@@@inlined_vector_internal@absl@@QEAAPEAUSubRange@3@_K@Z
+    ?AllocatedSize@CordRepFlat@cord_internal@absl@@QEBA_KXZ
     ?AlreadyExistsError@absl@@YA?AVStatus@1@Vstring_view@1@@Z
     ?AnnotateConstruct@NonEmptyInlinedStorage@?$FixedArray@PEAUCordRep@cord_internal@absl@@$0?0V?$allocator@PEAUCordRep@cord_internal@absl@@@__1@std@@@absl@@QEAAX_K@Z
     ?AnnotateDestruct@NonEmptyInlinedStorage@?$FixedArray@PEAUCordRep@cord_internal@absl@@$0?0V?$allocator@PEAUCordRep@cord_internal@absl@@@__1@std@@@absl@@QEAAX_K@Z
@@ -1461,6 +1463,7 @@
     ?CalculateBase64EscapedLenInternal@strings_internal@absl@@YA_K_K_N@Z
     ?CallVoidPtrFunction@Condition@absl@@CA_NPEBV12@@Z
     ?CancelledError@absl@@YA?AVStatus@1@Vstring_view@1@@Z
+    ?Capacity@CordRepFlat@cord_internal@absl@@QEBA_KXZ
     ?CatPieces@strings_internal@absl@@YA?AV?$basic_string@DU?$char_traits@D@__1@std@@V?$allocator@D@23@@__1@std@@V?$initializer_list@Vstring_view@absl@@@5@@Z
     ?Ceil@absl@@YA?AVDuration@1@V21@0@Z
     ?CheckInvariants@GraphCycles@synchronization_internal@absl@@QEBA_NXZ
@@ -1529,6 +1532,8 @@
     ?DecrementSynchSem@Mutex@absl@@CA_NPEAV12@PEAUPerThreadSynch@base_internal@2@VKernelTimeout@synchronization_internal@2@@Z
     ?DefaultArena@LowLevelAlloc@base_internal@absl@@SAPEAUArena@123@XZ
     ?DefaultStackUnwinder@absl@@YAHPEAPEAXPEAHHHPEBX1@Z
+    ?Delete@CordRepExternal@cord_internal@absl@@SAXPEAUCordRep@23@@Z
+    ?Delete@CordRepFlat@cord_internal@absl@@SAXPEAUCordRep@23@@Z
     ?DeleteArena@LowLevelAlloc@base_internal@absl@@SA_NPEAUArena@123@@Z
     ?Demangle@debugging_internal@absl@@YA_NPEBDPEADH@Z
     ?Description@Impl@time_zone@cctz@time_internal@absl@@QEBA?AV?$basic_string@DU?$char_traits@D@__1@std@@V?$allocator@D@23@@__1@std@@XZ
@@ -1920,6 +1925,7 @@
     ?Nanoseconds@absl@@YA?AVDuration@1@_J@Z
     ?NegateAndSubtractOne@time_internal@absl@@YA_J_J@Z
     ?Never@KernelTimeout@synchronization_internal@absl@@SA?AV123@XZ
+    ?New@CordRepFlat@cord_internal@absl@@SAPEAU123@_K@Z
     ?NewArena@LowLevelAlloc@base_internal@absl@@SAPEAUArena@123@H@Z
     ?NewRep@Status@absl@@CA_KW4StatusCode@2@Vstring_view@2@V?$unique_ptr@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@U?$default_delete@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@@__1@std@@@__1@std@@@Z
     ?NextCapacity@?$Storage@H$0CP@V?$allocator@H@__1@std@@@inlined_vector_internal@absl@@SA_K_K@Z
diff --git a/symbols_arm64_rel.def b/symbols_arm64_rel.def
index 669460e..f642c85 100644
--- a/symbols_arm64_rel.def
+++ b/symbols_arm64_rel.def
@@ -477,6 +477,7 @@
     ?MultiplyStep@?$BigUnsigned@$03@strings_internal@absl@@AEAAXHPEBIHH@Z
     ?MultiplyStep@?$BigUnsigned@$0FE@@strings_internal@absl@@AEAAXHPEBIHH@Z
     ?MutexDelay@synchronization_internal@absl@@YAHHH@Z
+    ?New@CordRepFlat@cord_internal@absl@@SAPEAU123@_K@Z
     ?NewArena@LowLevelAlloc@base_internal@absl@@SAPEAUArena@123@H@Z
     ?NewRep@Status@absl@@CA_KW4StatusCode@2@Vstring_view@2@V?$unique_ptr@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@U?$default_delete@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@@__1@std@@@__1@std@@@Z
     ?NextTransition@TimeZone@absl@@QEBA_NVTime@2@PEAUCivilTransition@12@@Z
diff --git a/symbols_x64_dbg.def b/symbols_x64_dbg.def
index 6c2662e..b622d5a 100644
--- a/symbols_x64_dbg.def
+++ b/symbols_x64_dbg.def
@@ -936,6 +936,7 @@
     ??0CordRep@cord_internal@absl@@QEAA@XZ
     ??0CordRepConcat@cord_internal@absl@@QEAA@XZ
     ??0CordRepExternal@cord_internal@absl@@QEAA@XZ
+    ??0CordRepFlat@cord_internal@absl@@QEAA@XZ
     ??0CordRepSubstring@cord_internal@absl@@QEAA@XZ
     ??0Duration@absl@@AEAA@_JI@Z
     ??0Duration@absl@@QEAA@XZ
@@ -1411,6 +1412,7 @@
     ?Allocate@?$AllocationTransaction@V?$allocator@PEBUCordRep@cord_internal@absl@@@__1@std@@@inlined_vector_internal@absl@@QEAAPEAPEBUCordRep@cord_internal@3@_K@Z
     ?Allocate@?$AllocationTransaction@V?$allocator@UPayload@status_internal@absl@@@__1@std@@@inlined_vector_internal@absl@@QEAAPEAUPayload@status_internal@3@_K@Z
     ?Allocate@?$AllocationTransaction@V?$allocator@USubRange@absl@@@__1@std@@@inlined_vector_internal@absl@@QEAAPEAUSubRange@3@_K@Z
+    ?AllocatedSize@CordRepFlat@cord_internal@absl@@QEBA_KXZ
     ?AlreadyExistsError@absl@@YA?AVStatus@1@Vstring_view@1@@Z
     ?AnnotateConstruct@NonEmptyInlinedStorage@?$FixedArray@PEAUCordRep@cord_internal@absl@@$0?0V?$allocator@PEAUCordRep@cord_internal@absl@@@__1@std@@@absl@@QEAAX_K@Z
     ?AnnotateDestruct@NonEmptyInlinedStorage@?$FixedArray@PEAUCordRep@cord_internal@absl@@$0?0V?$allocator@PEAUCordRep@cord_internal@absl@@@__1@std@@@absl@@QEAAX_K@Z
@@ -1462,6 +1464,7 @@
     ?CalculateBase64EscapedLenInternal@strings_internal@absl@@YA_K_K_N@Z
     ?CallVoidPtrFunction@Condition@absl@@CA_NPEBV12@@Z
     ?CancelledError@absl@@YA?AVStatus@1@Vstring_view@1@@Z
+    ?Capacity@CordRepFlat@cord_internal@absl@@QEBA_KXZ
     ?CatPieces@strings_internal@absl@@YA?AV?$basic_string@DU?$char_traits@D@__1@std@@V?$allocator@D@23@@__1@std@@V?$initializer_list@Vstring_view@absl@@@5@@Z
     ?Ceil@absl@@YA?AVDuration@1@V21@0@Z
     ?CheckInvariants@GraphCycles@synchronization_internal@absl@@QEBA_NXZ
@@ -1530,6 +1533,8 @@
     ?DecrementSynchSem@Mutex@absl@@CA_NPEAV12@PEAUPerThreadSynch@base_internal@2@VKernelTimeout@synchronization_internal@2@@Z
     ?DefaultArena@LowLevelAlloc@base_internal@absl@@SAPEAUArena@123@XZ
     ?DefaultStackUnwinder@absl@@YAHPEAPEAXPEAHHHPEBX1@Z
+    ?Delete@CordRepExternal@cord_internal@absl@@SAXPEAUCordRep@23@@Z
+    ?Delete@CordRepFlat@cord_internal@absl@@SAXPEAUCordRep@23@@Z
     ?DeleteArena@LowLevelAlloc@base_internal@absl@@SA_NPEAUArena@123@@Z
     ?Demangle@debugging_internal@absl@@YA_NPEBDPEADH@Z
     ?Description@Impl@time_zone@cctz@time_internal@absl@@QEBA?AV?$basic_string@DU?$char_traits@D@__1@std@@V?$allocator@D@23@@__1@std@@XZ
@@ -1920,6 +1925,7 @@
     ?Nanoseconds@absl@@YA?AVDuration@1@_J@Z
     ?NegateAndSubtractOne@time_internal@absl@@YA_J_J@Z
     ?Never@KernelTimeout@synchronization_internal@absl@@SA?AV123@XZ
+    ?New@CordRepFlat@cord_internal@absl@@SAPEAU123@_K@Z
     ?NewArena@LowLevelAlloc@base_internal@absl@@SAPEAUArena@123@H@Z
     ?NewRep@Status@absl@@CA_KW4StatusCode@2@Vstring_view@2@V?$unique_ptr@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@U?$default_delete@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@@__1@std@@@__1@std@@@Z
     ?NextCapacity@?$Storage@H$0CP@V?$allocator@H@__1@std@@@inlined_vector_internal@absl@@SA_K_K@Z
diff --git a/symbols_x64_rel.def b/symbols_x64_rel.def
index 2f91952..5ceb1dc 100644
--- a/symbols_x64_rel.def
+++ b/symbols_x64_rel.def
@@ -478,6 +478,7 @@
     ?MultiplyStep@?$BigUnsigned@$03@strings_internal@absl@@AEAAXHPEBIHH@Z
     ?MultiplyStep@?$BigUnsigned@$0FE@@strings_internal@absl@@AEAAXHPEBIHH@Z
     ?MutexDelay@synchronization_internal@absl@@YAHHH@Z
+    ?New@CordRepFlat@cord_internal@absl@@SAPEAU123@_K@Z
     ?NewArena@LowLevelAlloc@base_internal@absl@@SAPEAUArena@123@H@Z
     ?NewRep@Status@absl@@CA_KW4StatusCode@2@Vstring_view@2@V?$unique_ptr@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@U?$default_delete@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@@__1@std@@@__1@std@@@Z
     ?NextTransition@TimeZone@absl@@QEBA_NVTime@2@PEAUCivilTransition@12@@Z
diff --git a/symbols_x64_rel_asan.def b/symbols_x64_rel_asan.def
index aa14dc1..b036ba2 100644
--- a/symbols_x64_rel_asan.def
+++ b/symbols_x64_rel_asan.def
@@ -496,6 +496,7 @@
     ?MultiplyStep@?$BigUnsigned@$03@strings_internal@absl@@AEAAXHPEBIHH@Z
     ?MultiplyStep@?$BigUnsigned@$0FE@@strings_internal@absl@@AEAAXHPEBIHH@Z
     ?MutexDelay@synchronization_internal@absl@@YAHHH@Z
+    ?New@CordRepFlat@cord_internal@absl@@SAPEAU123@_K@Z
     ?NewArena@LowLevelAlloc@base_internal@absl@@SAPEAUArena@123@H@Z
     ?NewRep@Status@absl@@CA_KW4StatusCode@2@Vstring_view@2@V?$unique_ptr@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@U?$default_delete@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@@__1@std@@@__1@std@@@Z
     ?NextTransition@TimeZone@absl@@QEBA_NVTime@2@PEAUCivilTransition@12@@Z
diff --git a/symbols_x86_dbg.def b/symbols_x86_dbg.def
index cae5752..149eed1 100644
--- a/symbols_x86_dbg.def
+++ b/symbols_x86_dbg.def
@@ -934,6 +934,7 @@
     ??0CordRep@cord_internal@absl@@QAE@XZ
     ??0CordRepConcat@cord_internal@absl@@QAE@XZ
     ??0CordRepExternal@cord_internal@absl@@QAE@XZ
+    ??0CordRepFlat@cord_internal@absl@@QAE@XZ
     ??0CordRepSubstring@cord_internal@absl@@QAE@XZ
     ??0Duration@absl@@AAE@_JI@Z
     ??0Duration@absl@@QAE@XZ
@@ -1408,6 +1409,7 @@
     ?Allocate@?$AllocationTransaction@V?$allocator@PBUCordRep@cord_internal@absl@@@__1@std@@@inlined_vector_internal@absl@@QAEPAPBUCordRep@cord_internal@3@I@Z
     ?Allocate@?$AllocationTransaction@V?$allocator@UPayload@status_internal@absl@@@__1@std@@@inlined_vector_internal@absl@@QAEPAUPayload@status_internal@3@I@Z
     ?Allocate@?$AllocationTransaction@V?$allocator@USubRange@absl@@@__1@std@@@inlined_vector_internal@absl@@QAEPAUSubRange@3@I@Z
+    ?AllocatedSize@CordRepFlat@cord_internal@absl@@QBEIXZ
     ?AlreadyExistsError@absl@@YA?AVStatus@1@Vstring_view@1@@Z
     ?AnnotateConstruct@NonEmptyInlinedStorage@?$FixedArray@PAUCordRep@cord_internal@absl@@$0PPPPPPPP@V?$allocator@PAUCordRep@cord_internal@absl@@@__1@std@@@absl@@QAEXI@Z
     ?AnnotateDestruct@NonEmptyInlinedStorage@?$FixedArray@PAUCordRep@cord_internal@absl@@$0PPPPPPPP@V?$allocator@PAUCordRep@cord_internal@absl@@@__1@std@@@absl@@QAEXI@Z
@@ -1459,6 +1461,7 @@
     ?CalculateBase64EscapedLenInternal@strings_internal@absl@@YAII_N@Z
     ?CallVoidPtrFunction@Condition@absl@@CA_NPBV12@@Z
     ?CancelledError@absl@@YA?AVStatus@1@Vstring_view@1@@Z
+    ?Capacity@CordRepFlat@cord_internal@absl@@QBEIXZ
     ?CatPieces@strings_internal@absl@@YA?AV?$basic_string@DU?$char_traits@D@__1@std@@V?$allocator@D@23@@__1@std@@V?$initializer_list@Vstring_view@absl@@@5@@Z
     ?Ceil@absl@@YA?AVDuration@1@V21@0@Z
     ?CheckInvariants@GraphCycles@synchronization_internal@absl@@QBE_NXZ
@@ -1527,6 +1530,8 @@
     ?DecrementSynchSem@Mutex@absl@@CA_NPAV12@PAUPerThreadSynch@base_internal@2@VKernelTimeout@synchronization_internal@2@@Z
     ?DefaultArena@LowLevelAlloc@base_internal@absl@@SAPAUArena@123@XZ
     ?DefaultStackUnwinder@absl@@YAHPAPAXPAHHHPBX1@Z
+    ?Delete@CordRepExternal@cord_internal@absl@@SAXPAUCordRep@23@@Z
+    ?Delete@CordRepFlat@cord_internal@absl@@SAXPAUCordRep@23@@Z
     ?DeleteArena@LowLevelAlloc@base_internal@absl@@SA_NPAUArena@123@@Z
     ?Demangle@debugging_internal@absl@@YA_NPBDPADH@Z
     ?Description@Impl@time_zone@cctz@time_internal@absl@@QBE?AV?$basic_string@DU?$char_traits@D@__1@std@@V?$allocator@D@23@@__1@std@@XZ
@@ -1917,6 +1922,7 @@
     ?Nanoseconds@absl@@YA?AVDuration@1@_J@Z
     ?NegateAndSubtractOne@time_internal@absl@@YA_J_J@Z
     ?Never@KernelTimeout@synchronization_internal@absl@@SA?AV123@XZ
+    ?New@CordRepFlat@cord_internal@absl@@SAPAU123@I@Z
     ?NewArena@LowLevelAlloc@base_internal@absl@@SAPAUArena@123@H@Z
     ?NewRep@Status@absl@@CAIW4StatusCode@2@Vstring_view@2@V?$unique_ptr@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@U?$default_delete@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@@__1@std@@@__1@std@@@Z
     ?NextCapacity@?$Storage@H$0CP@V?$allocator@H@__1@std@@@inlined_vector_internal@absl@@SAII@Z
diff --git a/symbols_x86_rel.def b/symbols_x86_rel.def
index 8f2ea9c..3ef1152 100644
--- a/symbols_x86_rel.def
+++ b/symbols_x86_rel.def
@@ -474,6 +474,7 @@
     ?MultiplyStep@?$BigUnsigned@$03@strings_internal@absl@@AAEXHPBIHH@Z
     ?MultiplyStep@?$BigUnsigned@$0FE@@strings_internal@absl@@AAEXHPBIHH@Z
     ?MutexDelay@synchronization_internal@absl@@YAHHH@Z
+    ?New@CordRepFlat@cord_internal@absl@@SAPAU123@I@Z
     ?NewArena@LowLevelAlloc@base_internal@absl@@SAPAUArena@123@H@Z
     ?NewRep@Status@absl@@CAIW4StatusCode@2@Vstring_view@2@V?$unique_ptr@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@U?$default_delete@V?$InlinedVector@UPayload@status_internal@absl@@$00V?$allocator@UPayload@status_internal@absl@@@__1@std@@@absl@@@__1@std@@@__1@std@@@Z
     ?NextTransition@TimeZone@absl@@QBE_NVTime@2@PAUCivilTransition@12@@Z