diff --git a/http2/hpack/decoder/hpack_block_decoder.cc b/http2/hpack/decoder/hpack_block_decoder.cc
index 509a493..3211daa 100644
--- a/http2/hpack/decoder/hpack_block_decoder.cc
+++ b/http2/hpack/decoder/hpack_block_decoder.cc
@@ -6,10 +6,10 @@
 
 #include <cstdint>
 
+#include "absl/strings/str_cat.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_flags.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_logging.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_string_utils.h"
-#include "net/third_party/quiche/src/common/platform/api/quiche_str_cat.h"
 
 namespace http2 {
 
@@ -53,7 +53,7 @@
 }
 
 std::string HpackBlockDecoder::DebugString() const {
-  return quiche::QuicheStrCat(
+  return absl::StrCat(
       "HpackBlockDecoder(", entry_decoder_.DebugString(), ", listener@",
       Http2Hex(reinterpret_cast<intptr_t>(listener_)),
       (before_entry_ ? ", between entries)" : ", in an entry)"));
diff --git a/http2/hpack/decoder/hpack_entry_type_decoder.cc b/http2/hpack/decoder/hpack_entry_type_decoder.cc
index 5df119f..c2fe470 100644
--- a/http2/hpack/decoder/hpack_entry_type_decoder.cc
+++ b/http2/hpack/decoder/hpack_entry_type_decoder.cc
@@ -4,16 +4,16 @@
 
 #include "net/third_party/quiche/src/http2/hpack/decoder/hpack_entry_type_decoder.h"
 
+#include "absl/strings/str_cat.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_bug_tracker.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_flags.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_logging.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_string_utils.h"
-#include "net/third_party/quiche/src/common/platform/api/quiche_str_cat.h"
 
 namespace http2 {
 
 std::string HpackEntryTypeDecoder::DebugString() const {
-  return quiche::QuicheStrCat(
+  return absl::StrCat(
       "HpackEntryTypeDecoder(varint_decoder=", varint_decoder_.DebugString(),
       ", entry_type=", entry_type_, ")");
 }
diff --git a/http2/hpack/decoder/hpack_string_decoder.cc b/http2/hpack/decoder/hpack_string_decoder.cc
index ad5bb54..bc1e43b 100644
--- a/http2/hpack/decoder/hpack_string_decoder.cc
+++ b/http2/hpack/decoder/hpack_string_decoder.cc
@@ -4,15 +4,15 @@
 
 #include "net/third_party/quiche/src/http2/hpack/decoder/hpack_string_decoder.h"
 
-#include "net/third_party/quiche/src/common/platform/api/quiche_str_cat.h"
+#include "absl/strings/str_cat.h"
 
 namespace http2 {
 
 std::string HpackStringDecoder::DebugString() const {
-  return quiche::QuicheStrCat(
-      "HpackStringDecoder(state=", StateToString(state_),
-      ", length=", length_decoder_.DebugString(), ", remaining=", remaining_,
-      ", huffman=", huffman_encoded_ ? "true)" : "false)");
+  return absl::StrCat("HpackStringDecoder(state=", StateToString(state_),
+                      ", length=", length_decoder_.DebugString(),
+                      ", remaining=", remaining_,
+                      ", huffman=", huffman_encoded_ ? "true)" : "false)");
 }
 
 // static
@@ -25,7 +25,7 @@
     case kResumeDecodingLength:
       return "kResumeDecodingLength";
   }
-  return quiche::QuicheStrCat("UNKNOWN_STATE(", static_cast<uint32_t>(v), ")");
+  return absl::StrCat("UNKNOWN_STATE(", static_cast<uint32_t>(v), ")");
 }
 
 std::ostream& operator<<(std::ostream& out, const HpackStringDecoder& v) {
diff --git a/http2/hpack/decoder/hpack_whole_entry_buffer.cc b/http2/hpack/decoder/hpack_whole_entry_buffer.cc
index ecdcdc9..4d54b16 100644
--- a/http2/hpack/decoder/hpack_whole_entry_buffer.cc
+++ b/http2/hpack/decoder/hpack_whole_entry_buffer.cc
@@ -4,12 +4,12 @@
 
 #include "net/third_party/quiche/src/http2/hpack/decoder/hpack_whole_entry_buffer.h"
 
+#include "absl/strings/str_cat.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_estimate_memory_usage.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_flags.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_logging.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_macros.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_string_utils.h"
-#include "net/third_party/quiche/src/common/platform/api/quiche_str_cat.h"
 
 namespace http2 {
 
@@ -92,7 +92,7 @@
                  << (huffman_encoded ? "true" : "false") << ",  len=" << len;
   if (!error_detected_) {
     if (len > max_string_size_bytes_) {
-      std::string detailed_error = quiche::QuicheStrCat(
+      std::string detailed_error = absl::StrCat(
           "Value length (", len, ") of [", name_.GetStringIfComplete(),
           "] is longer than permitted (", max_string_size_bytes_, ")");
       HTTP2_DVLOG(1) << detailed_error;
diff --git a/http2/http2_constants.cc b/http2/http2_constants.cc
index 08351c4..61481e4 100644
--- a/http2/http2_constants.cc
+++ b/http2/http2_constants.cc
@@ -4,10 +4,10 @@
 
 #include "net/third_party/quiche/src/http2/http2_constants.h"
 
+#include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_logging.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_string_utils.h"
-#include "net/third_party/quiche/src/common/platform/api/quiche_str_cat.h"
 
 namespace http2 {
 
@@ -36,7 +36,7 @@
     case Http2FrameType::ALTSVC:
       return "ALTSVC";
   }
-  return quiche::QuicheStrCat("UnknownFrameType(", static_cast<int>(v), ")");
+  return absl::StrCat("UnknownFrameType(", static_cast<int>(v), ")");
 }
 
 std::string Http2FrameTypeToString(uint8_t v) {
@@ -121,7 +121,7 @@
     case 0xd:
       return "HTTP_1_1_REQUIRED";
   }
-  return quiche::QuicheStrCat("UnknownErrorCode(0x", Http2Hex(v), ")");
+  return absl::StrCat("UnknownErrorCode(0x", Http2Hex(v), ")");
 }
 std::string Http2ErrorCodeToString(Http2ErrorCode v) {
   return Http2ErrorCodeToString(static_cast<uint32_t>(v));
@@ -142,7 +142,7 @@
     case 0x6:
       return "MAX_HEADER_LIST_SIZE";
   }
-  return quiche::QuicheStrCat("UnknownSettingsParameter(0x", Http2Hex(v), ")");
+  return absl::StrCat("UnknownSettingsParameter(0x", Http2Hex(v), ")");
 }
 std::string Http2SettingsParameterToString(Http2SettingsParameter v) {
   return Http2SettingsParameterToString(static_cast<uint32_t>(v));
diff --git a/http2/http2_structures.cc b/http2/http2_structures.cc
index 3558331..7d4f745 100644
--- a/http2/http2_structures.cc
+++ b/http2/http2_structures.cc
@@ -7,8 +7,8 @@
 #include <cstring>  // For std::memcmp
 #include <sstream>
 
+#include "absl/strings/str_cat.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_string_utils.h"
-#include "net/third_party/quiche/src/common/platform/api/quiche_str_cat.h"
 
 namespace http2 {
 
@@ -21,9 +21,9 @@
 }
 
 std::string Http2FrameHeader::ToString() const {
-  return quiche::QuicheStrCat(
-      "length=", payload_length, ", type=", Http2FrameTypeToString(type),
-      ", flags=", FlagsToString(), ", stream=", stream_id);
+  return absl::StrCat("length=", payload_length,
+                      ", type=", Http2FrameTypeToString(type),
+                      ", flags=", FlagsToString(), ", stream=", stream_id);
 }
 
 std::string Http2FrameHeader::FlagsToString() const {
diff --git a/http2/http2_structures_test.cc b/http2/http2_structures_test.cc
index 6b060cf..97b7b34 100644
--- a/http2/http2_structures_test.cc
+++ b/http2/http2_structures_test.cc
@@ -19,11 +19,11 @@
 #include <type_traits>
 #include <vector>
 
+#include "absl/strings/str_cat.h"
 #include "net/third_party/quiche/src/http2/http2_structures_test_util.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_string_utils.h"
 #include "net/third_party/quiche/src/http2/platform/api/http2_test_helpers.h"
 #include "net/third_party/quiche/src/http2/test_tools/http2_random.h"
-#include "net/third_party/quiche/src/common/platform/api/quiche_str_cat.h"
 #include "net/third_party/quiche/src/common/platform/api/quiche_test.h"
 
 using ::testing::AssertionResult;
@@ -441,8 +441,7 @@
 
   std::stringstream s;
   s << v;
-  EXPECT_EQ(quiche::QuicheStrCat("promised_stream_id=", promised_stream_id),
-            s.str());
+  EXPECT_EQ(absl::StrCat("promised_stream_id=", promised_stream_id), s.str());
 
   // High-bit is reserved, but not used, so we can set it.
   promised_stream_id |= 0x80000000;
@@ -499,9 +498,8 @@
 
   std::stringstream s;
   s << v;
-  EXPECT_EQ(
-      quiche::QuicheStrCat("window_size_increment=", window_size_increment),
-      s.str());
+  EXPECT_EQ(absl::StrCat("window_size_increment=", window_size_increment),
+            s.str());
 
   // High-bit is reserved, but not used, so we can set it.
   window_size_increment |= 0x80000000;
@@ -525,7 +523,7 @@
 
   std::stringstream s;
   s << v;
-  EXPECT_EQ(quiche::QuicheStrCat("origin_length=", origin_length), s.str());
+  EXPECT_EQ(absl::StrCat("origin_length=", origin_length), s.str());
 
   Http2AltSvcFields w{++origin_length};
   EXPECT_EQ(w, w);
diff --git a/quic/masque/masque_client_bin.cc b/quic/masque/masque_client_bin.cc
index 0e44092..f0eda82 100644
--- a/quic/masque/masque_client_bin.cc
+++ b/quic/masque/masque_client_bin.cc
@@ -9,6 +9,7 @@
 
 #include <memory>
 
+#include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
 #include "net/third_party/quiche/src/quic/core/quic_server_id.h"
 #include "net/third_party/quiche/src/quic/masque/masque_client_tools.h"
@@ -21,7 +22,6 @@
 #include "net/third_party/quiche/src/quic/platform/api/quic_system_event_loop.h"
 #include "net/third_party/quiche/src/quic/tools/fake_proof_verifier.h"
 #include "net/third_party/quiche/src/quic/tools/quic_url.h"
-#include "net/third_party/quiche/src/common/platform/api/quiche_str_cat.h"
 #include "net/third_party/quiche/src/common/platform/api/quiche_text_utils.h"
 
 DEFINE_QUIC_COMMAND_LINE_FLAG(bool,
@@ -51,7 +51,7 @@
 
   QuicUrl masque_url(urls[0], "https");
   if (masque_url.host().empty()) {
-    masque_url = QuicUrl(quiche::QuicheStrCat("https://", urls[0]), "https");
+    masque_url = QuicUrl(absl::StrCat("https://", urls[0]), "https");
   }
   if (masque_url.host().empty()) {
     QUIC_LOG(ERROR) << "Failed to parse MASQUE server address " << urls[0];
diff --git a/quic/masque/masque_client_tools.cc b/quic/masque/masque_client_tools.cc
index e59204a..b8aec5c 100644
--- a/quic/masque/masque_client_tools.cc
+++ b/quic/masque/masque_client_tools.cc
@@ -26,7 +26,7 @@
 
   // Build the client, and try to connect.
   const QuicSocketAddress addr =
-      LookupAddress(url.host(), quiche::QuicheStrCat(url.port()));
+      LookupAddress(url.host(), absl::StrCat(url.port()));
   if (!addr.IsInitialized()) {
     QUIC_LOG(ERROR) << "Unable to resolve address: " << url.host();
     return false;
diff --git a/quic/masque/masque_epoll_client.cc b/quic/masque/masque_epoll_client.cc
index 3b7c201..7d4f145 100644
--- a/quic/masque/masque_epoll_client.cc
+++ b/quic/masque/masque_epoll_client.cc
@@ -47,8 +47,7 @@
     QuicEpollServer* epoll_server,
     std::unique_ptr<ProofVerifier> proof_verifier) {
   // Build the masque_client, and try to connect.
-  QuicSocketAddress addr =
-      tools::LookupAddress(host, quiche::QuicheStrCat(port));
+  QuicSocketAddress addr = tools::LookupAddress(host, absl::StrCat(port));
   if (!addr.IsInitialized()) {
     QUIC_LOG(ERROR) << "Unable to resolve address: " << host;
     return nullptr;
@@ -59,7 +58,7 @@
   // MasqueEpollClient is private and therefore not accessible from make_unique.
   auto masque_client = QuicWrapUnique(new MasqueEpollClient(
       addr, server_id, epoll_server, std::move(proof_verifier),
-      quiche::QuicheStrCat(host, ":", port)));
+      absl::StrCat(host, ":", port)));
 
   if (masque_client == nullptr) {
     QUIC_LOG(ERROR) << "Failed to create masque_client";
diff --git a/quic/masque/masque_server_backend.cc b/quic/masque/masque_server_backend.cc
index fc2fdc0..86a7ff5 100644
--- a/quic/masque/masque_server_backend.cc
+++ b/quic/masque/masque_server_backend.cc
@@ -3,8 +3,8 @@
 // found in the LICENSE file.
 
 #include "net/third_party/quiche/src/quic/masque/masque_server_backend.h"
+#include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
-#include "net/third_party/quiche/src/common/platform/api/quiche_str_cat.h"
 
 namespace quic {
 
@@ -12,9 +12,9 @@
 
 std::string GetRequestHandlerKey(
     const QuicSimpleServerBackend::RequestHandler* request_handler) {
-  return quiche::QuicheStrCat(request_handler->connection_id().ToString(), "_",
-                              request_handler->stream_id(), "_",
-                              request_handler->peer_host());
+  return absl::StrCat(request_handler->connection_id().ToString(), "_",
+                      request_handler->stream_id(), "_",
+                      request_handler->peer_host());
 }
 
 }  // namespace