diff --git a/adb/client/file_sync_client.cpp b/adb/client/file_sync_client.cpp
index 94bd8f5..ed4a1fe 100644
--- a/adb/client/file_sync_client.cpp
+++ b/adb/client/file_sync_client.cpp
@@ -53,6 +53,8 @@
 #include <android-base/strings.h>
 #include <android-base/stringprintf.h>
 
+using namespace std::literals;
+
 typedef void(sync_ls_cb)(unsigned mode, uint64_t size, uint64_t time, const char* name);
 
 struct syncsendbuf {
@@ -112,8 +114,12 @@
     uint64_t bytes_transferred;
     uint64_t bytes_expected;
     bool expect_multiple_files;
-    std::string last_progress_str;
 
+  private:
+    std::string last_progress_str;
+    std::chrono::steady_clock::time_point last_progress_time;
+
+  public:
     TransferLedger() {
         Reset();
     }
@@ -128,12 +134,13 @@
     }
 
     void Reset() {
-        last_progress_str.clear();
         start_time = std::chrono::steady_clock::now();
         files_transferred = 0;
         files_skipped = 0;
         bytes_transferred = 0;
         bytes_expected = 0;
+        last_progress_str.clear();
+        last_progress_time = {};
     }
 
     std::string TransferRate() {
@@ -153,6 +160,12 @@
 
     void ReportProgress(LinePrinter& lp, const std::string& file, uint64_t file_copied_bytes,
                         uint64_t file_total_bytes) {
+        static constexpr auto kProgressReportInterval = 100ms;
+
+        auto now = std::chrono::steady_clock::now();
+        if (now < last_progress_time + kProgressReportInterval) {
+            return;
+        }
         char overall_percentage_str[5] = "?";
         if (bytes_expected != 0 && bytes_transferred <= bytes_expected) {
             int overall_percentage = static_cast<int>(bytes_transferred * 100 / bytes_expected);
@@ -186,6 +199,7 @@
         if (output != last_progress_str) {
             lp.Print(output, LinePrinter::LineType::INFO);
             last_progress_str = std::move(output);
+            last_progress_time = now;
         }
     }
 
@@ -209,7 +223,8 @@
 
 class SyncConnection {
   public:
-    SyncConnection() {
+    SyncConnection() : acknowledgement_buffer_(sizeof(sync_status) + SYNC_DATA_MAX) {
+        acknowledgement_buffer_.resize(0);
         max = SYNC_DATA_MAX; // TODO: decide at runtime.
 
         std::string error;
@@ -507,34 +522,6 @@
         return WriteOrDie(lpath, rpath, &msg.data, sizeof(msg.data));
     }
 
-    bool ReadAcknowledgments() {
-        bool result = true;
-        while (!deferred_acknowledgements_.empty()) {
-            auto [from, to] = std::move(deferred_acknowledgements_.front());
-            deferred_acknowledgements_.pop_front();
-            result &= CopyDone(from, to);
-        }
-        return result;
-    }
-
-    bool CopyDone(const std::string& from, const std::string& to) {
-        syncmsg msg;
-        if (!ReadFdExactly(fd, &msg.status, sizeof(msg.status))) {
-            Error("failed to copy '%s' to '%s': couldn't read from device", from.c_str(),
-                  to.c_str());
-            return false;
-        }
-        if (msg.status.id == ID_OKAY) {
-            return true;
-        }
-        if (msg.status.id != ID_FAIL) {
-            Error("failed to copy '%s' to '%s': unknown reason %d", from.c_str(), to.c_str(),
-                  msg.status.id);
-            return false;
-        }
-        return ReportCopyFailure(from, to, msg);
-    }
-
     bool ReportCopyFailure(const std::string& from, const std::string& to, const syncmsg& msg) {
         std::vector<char> buf(msg.status.msglen + 1);
         if (!ReadFdExactly(fd, &buf[0], msg.status.msglen)) {
@@ -547,6 +534,97 @@
         return false;
     }
 
+    void CopyDone() { deferred_acknowledgements_.pop_front(); }
+
+    void ReportDeferredCopyFailure(const std::string& msg) {
+        auto& [from, to] = deferred_acknowledgements_.front();
+        Error("failed to copy '%s' to '%s': remote %s", from.c_str(), to.c_str(), msg.c_str());
+        deferred_acknowledgements_.pop_front();
+    }
+
+    bool ReadAcknowledgements(bool read_all = false) {
+        // We need to read enough such that adbd's intermediate socket's write buffer can't be
+        // full. The default buffer on Linux is 212992 bytes, but there's 576 bytes of bookkeeping
+        // overhead per write. The worst case scenario is a continuous string of failures, since
+        // each logical packet is divided into two writes. If our packet size if conservatively 512
+        // bytes long, this leaves us with space for 128 responses.
+        constexpr size_t max_deferred_acks = 128;
+        auto& buf = acknowledgement_buffer_;
+        adb_pollfd pfd = {.fd = fd.get(), .events = POLLIN};
+        while (!deferred_acknowledgements_.empty()) {
+            bool should_block = read_all || deferred_acknowledgements_.size() >= max_deferred_acks;
+
+            ssize_t rc = adb_poll(&pfd, 1, should_block ? -1 : 0);
+            if (rc == 0) {
+                CHECK(!should_block);
+                return true;
+            }
+
+            if (acknowledgement_buffer_.size() < sizeof(sync_status)) {
+                const ssize_t header_bytes_left = sizeof(sync_status) - buf.size();
+                ssize_t rc = adb_read(fd, buf.end(), header_bytes_left);
+                if (rc <= 0) {
+                    Error("failed to read copy response");
+                    return false;
+                }
+
+                buf.resize(buf.size() + rc);
+                if (rc != header_bytes_left) {
+                    // Early exit if we run out of data in the socket.
+                    return true;
+                }
+
+                if (!should_block) {
+                    // We don't want to read again yet, because the socket might be empty.
+                    continue;
+                }
+            }
+
+            auto* hdr = reinterpret_cast<sync_status*>(buf.data());
+            if (hdr->id == ID_OKAY) {
+                buf.resize(0);
+                if (hdr->msglen != 0) {
+                    Error("received ID_OKAY with msg_len (%" PRIu32 " != 0", hdr->msglen);
+                    return false;
+                }
+                CopyDone();
+                continue;
+            } else if (hdr->id != ID_FAIL) {
+                Error("unexpected response from daemon: id = %#" PRIx32, hdr->id);
+                return false;
+            } else if (hdr->msglen > SYNC_DATA_MAX) {
+                Error("too-long message length from daemon: msglen = %" PRIu32, hdr->msglen);
+                return false;
+            }
+
+            const ssize_t msg_bytes_left = hdr->msglen + sizeof(sync_status) - buf.size();
+            CHECK_GE(msg_bytes_left, 0);
+            if (msg_bytes_left > 0) {
+                ssize_t rc = adb_read(fd, buf.end(), msg_bytes_left);
+                if (rc <= 0) {
+                    Error("failed to read copy failure message");
+                    return false;
+                }
+
+                buf.resize(buf.size() + rc);
+                if (rc != msg_bytes_left) {
+                    if (should_block) {
+                        continue;
+                    } else {
+                        return true;
+                    }
+                }
+
+                std::string msg(buf.begin() + sizeof(sync_status), buf.end());
+                ReportDeferredCopyFailure(msg);
+                buf.resize(0);
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     void Printf(const char* fmt, ...) __attribute__((__format__(__printf__, 2, 3))) {
         std::string s;
 
@@ -613,6 +691,7 @@
 
   private:
     std::deque<std::pair<std::string, std::string>> deferred_acknowledgements_;
+    Block acknowledgement_buffer_;
     FeatureSet features_;
     bool have_stat_v2_;
     bool have_ls_v2_;
@@ -721,7 +800,7 @@
         if (!sc.SendSmallFile(rpath, mode, lpath, rpath, mtime, buf, data_length)) {
             return false;
         }
-        return true;
+        return sc.ReadAcknowledgements();
 #endif
     }
 
@@ -744,7 +823,7 @@
             return false;
         }
     }
-    return true;
+    return sc.ReadAcknowledgements();
 }
 
 static bool sync_recv(SyncConnection& sc, const char* rpath, const char* lpath,
@@ -971,8 +1050,9 @@
     }
 
     sc.RecordFilesSkipped(skipped);
+    bool success = sc.ReadAcknowledgements(true);
     sc.ReportTransferRate(lpath, TransferDirection::push);
-    return true;
+    return success;
 }
 
 bool do_sync_push(const std::vector<const char*>& srcs, const char* dst, bool sync) {
@@ -1065,7 +1145,7 @@
         sc.ReportTransferRate(src_path, TransferDirection::push);
     }
 
-    success &= sc.ReadAcknowledgments();
+    success &= sc.ReadAcknowledgements(true);
     sc.ReportOverallTransferRate(TransferDirection::push);
     return success;
 }
diff --git a/adb/file_sync_protocol.h b/adb/file_sync_protocol.h
index 508c138..87ede0c 100644
--- a/adb/file_sync_protocol.h
+++ b/adb/file_sync_protocol.h
@@ -41,57 +41,69 @@
     // Followed by 'path_length' bytes of path (not NUL-terminated).
 } __attribute__((packed));
 
+struct __attribute__((packed)) sync_stat_v1 {
+    uint32_t id;
+    uint32_t mode;
+    uint32_t size;
+    uint32_t mtime;
+};
+
+struct __attribute__((packed)) sync_stat_v2 {
+    uint32_t id;
+    uint32_t error;
+    uint64_t dev;
+    uint64_t ino;
+    uint32_t mode;
+    uint32_t nlink;
+    uint32_t uid;
+    uint32_t gid;
+    uint64_t size;
+    int64_t atime;
+    int64_t mtime;
+    int64_t ctime;
+};
+
+struct __attribute__((packed)) sync_dent_v1 {
+    uint32_t id;
+    uint32_t mode;
+    uint32_t size;
+    uint32_t mtime;
+    uint32_t namelen;
+};  // followed by `namelen` bytes of the name.
+
+struct __attribute__((packed)) sync_dent_v2 {
+    uint32_t id;
+    uint32_t error;
+    uint64_t dev;
+    uint64_t ino;
+    uint32_t mode;
+    uint32_t nlink;
+    uint32_t uid;
+    uint32_t gid;
+    uint64_t size;
+    int64_t atime;
+    int64_t mtime;
+    int64_t ctime;
+    uint32_t namelen;
+};  // followed by `namelen` bytes of the name.
+
+struct __attribute__((packed)) sync_data {
+    uint32_t id;
+    uint32_t size;
+};  // followed by `size` bytes of data.
+
+struct __attribute__((packed)) sync_status {
+    uint32_t id;
+    uint32_t msglen;
+};  // followed by `msglen` bytes of error message, if id == ID_FAIL.
+
 union syncmsg {
-    struct __attribute__((packed)) {
-        uint32_t id;
-        uint32_t mode;
-        uint32_t size;
-        uint32_t mtime;
-    } stat_v1;
-    struct __attribute__((packed)) {
-        uint32_t id;
-        uint32_t error;
-        uint64_t dev;
-        uint64_t ino;
-        uint32_t mode;
-        uint32_t nlink;
-        uint32_t uid;
-        uint32_t gid;
-        uint64_t size;
-        int64_t atime;
-        int64_t mtime;
-        int64_t ctime;
-    } stat_v2;
-    struct __attribute__((packed)) {
-        uint32_t id;
-        uint32_t mode;
-        uint32_t size;
-        uint32_t mtime;
-        uint32_t namelen;
-    } dent_v1; // followed by `namelen` bytes of the name.
-    struct __attribute__((packed)) {
-        uint32_t id;
-        uint32_t error;
-        uint64_t dev;
-        uint64_t ino;
-        uint32_t mode;
-        uint32_t nlink;
-        uint32_t uid;
-        uint32_t gid;
-        uint64_t size;
-        int64_t atime;
-        int64_t mtime;
-        int64_t ctime;
-        uint32_t namelen;
-    } dent_v2; // followed by `namelen` bytes of the name.
-    struct __attribute__((packed)) {
-        uint32_t id;
-        uint32_t size;
-    } data; // followed by `size` bytes of data.
-    struct __attribute__((packed)) {
-        uint32_t id;
-        uint32_t msglen;
-    } status; // followed by `msglen` bytes of error message, if id == ID_FAIL.
+    sync_stat_v1 stat_v1;
+    sync_stat_v2 stat_v2;
+    sync_dent_v1 dent_v1;
+    sync_dent_v2 dent_v2;
+    sync_data data;
+    sync_status status;
 };
 
 #define SYNC_DATA_MAX (64 * 1024)
diff --git a/libstats/pull/Android.bp b/libstats/pull/Android.bp
index 0fb8f1b..a7b5d91 100644
--- a/libstats/pull/Android.bp
+++ b/libstats/pull/Android.bp
@@ -53,6 +53,10 @@
         "com.android.os.statsd",
         "test_com.android.os.statsd",
     ],
+    // TODO(b/151102177): Enable it when the build error is fixed.
+    header_abi_checker: {
+        enabled: false,
+    },
 }
 
 // ONLY USE IN TESTS.
@@ -86,4 +90,4 @@
         "-Wno-unused-function",
         "-Wno-unused-parameter",
     ],
-}
\ No newline at end of file
+}
diff --git a/libunwindstack/DexFile.cpp b/libunwindstack/DexFile.cpp
index dff7a8b..bf63abf 100644
--- a/libunwindstack/DexFile.cpp
+++ b/libunwindstack/DexFile.cpp
@@ -89,7 +89,7 @@
     return nullptr;
   }
 
-  return std::unique_ptr<DexFileFromFile>(new DexFileFromFile(std::move(*art_dex_file.release())));
+  return std::unique_ptr<DexFileFromFile>(new DexFileFromFile(art_dex_file));
 }
 
 std::unique_ptr<DexFileFromMemory> DexFileFromMemory::Create(uint64_t dex_file_offset_in_memory,
@@ -108,7 +108,7 @@
 
     if (art_dex_file != nullptr) {
       return std::unique_ptr<DexFileFromMemory>(
-          new DexFileFromMemory(std::move(*art_dex_file.release()), std::move(backing_memory)));
+          new DexFileFromMemory(art_dex_file, std::move(backing_memory)));
     }
 
     if (!error_msg.empty()) {
diff --git a/libunwindstack/DexFile.h b/libunwindstack/DexFile.h
index ca658e6..4e8369f 100644
--- a/libunwindstack/DexFile.h
+++ b/libunwindstack/DexFile.h
@@ -39,7 +39,8 @@
                                          MapInfo* info);
 
  protected:
-  DexFile(art_api::dex::DexFile&& art_dex_file) : art_api::dex::DexFile(std::move(art_dex_file)) {}
+  DexFile(std::unique_ptr<art_api::dex::DexFile>& art_dex_file)
+      : art_api::dex::DexFile(art_dex_file) {}
 };
 
 class DexFileFromFile : public DexFile {
@@ -48,7 +49,7 @@
                                                  const std::string& file);
 
  private:
-  DexFileFromFile(art_api::dex::DexFile&& art_dex_file) : DexFile(std::move(art_dex_file)) {}
+  DexFileFromFile(std::unique_ptr<art_api::dex::DexFile>& art_dex_file) : DexFile(art_dex_file) {}
 };
 
 class DexFileFromMemory : public DexFile {
@@ -57,8 +58,9 @@
                                                    Memory* memory, const std::string& name);
 
  private:
-  DexFileFromMemory(art_api::dex::DexFile&& art_dex_file, std::vector<uint8_t>&& memory)
-      : DexFile(std::move(art_dex_file)), memory_(std::move(memory)) {}
+  DexFileFromMemory(std::unique_ptr<art_api::dex::DexFile>& art_dex_file,
+                    std::vector<uint8_t>&& memory)
+      : DexFile(art_dex_file), memory_(std::move(memory)) {}
 
   std::vector<uint8_t> memory_;
 };
diff --git a/libunwindstack/tests/DexFileTest.cpp b/libunwindstack/tests/DexFileTest.cpp
index 1b54da6..dc935a3 100644
--- a/libunwindstack/tests/DexFileTest.cpp
+++ b/libunwindstack/tests/DexFileTest.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include <malloc.h>
 #include <stdint.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ -72,6 +73,37 @@
   EXPECT_TRUE(DexFileFromFile::Create(0x100, tf.path) != nullptr);
 }
 
+static constexpr size_t kNumLeakLoops = 5000;
+static constexpr size_t kMaxAllowedLeakBytes = 1024;
+
+static void CheckForLeak(size_t loop, size_t* first_allocated_bytes, size_t* last_allocated_bytes) {
+  size_t allocated_bytes = mallinfo().uordblks;
+  if (*first_allocated_bytes == 0) {
+    *first_allocated_bytes = allocated_bytes;
+  } else if (*last_allocated_bytes > *first_allocated_bytes) {
+    // Check that the total memory did not increase too much over the first loop.
+    ASSERT_LE(*last_allocated_bytes - *first_allocated_bytes, kMaxAllowedLeakBytes)
+        << "Failed in loop " << loop << " first_allocated_bytes " << *first_allocated_bytes
+        << " last_allocated_bytes " << *last_allocated_bytes;
+  }
+  *last_allocated_bytes = allocated_bytes;
+}
+
+TEST(DexFileTest, from_file_no_leak) {
+  TemporaryFile tf;
+  ASSERT_TRUE(tf.fd != -1);
+
+  ASSERT_EQ(sizeof(kDexData),
+            static_cast<size_t>(TEMP_FAILURE_RETRY(write(tf.fd, kDexData, sizeof(kDexData)))));
+
+  size_t first_allocated_bytes = 0;
+  size_t last_allocated_bytes = 0;
+  for (size_t i = 0; i < kNumLeakLoops; i++) {
+    EXPECT_TRUE(DexFileFromFile::Create(0, tf.path) != nullptr);
+    ASSERT_NO_FATAL_FAILURE(CheckForLeak(i, &first_allocated_bytes, &last_allocated_bytes));
+  }
+}
+
 TEST(DexFileTest, from_memory_fail_too_small_for_header) {
   MemoryFake memory;
 
@@ -96,6 +128,19 @@
   EXPECT_TRUE(DexFileFromMemory::Create(0x1000, &memory, "") != nullptr);
 }
 
+TEST(DexFileTest, from_memory_no_leak) {
+  MemoryFake memory;
+
+  memory.SetMemory(0x1000, kDexData, sizeof(kDexData));
+
+  size_t first_allocated_bytes = 0;
+  size_t last_allocated_bytes = 0;
+  for (size_t i = 0; i < kNumLeakLoops; i++) {
+    EXPECT_TRUE(DexFileFromMemory::Create(0x1000, &memory, "") != nullptr);
+    ASSERT_NO_FATAL_FAILURE(CheckForLeak(i, &first_allocated_bytes, &last_allocated_bytes));
+  }
+}
+
 TEST(DexFileTest, create_using_file) {
   TemporaryFile tf;
   ASSERT_TRUE(tf.fd != -1);