diff --git a/base/common/ReplxxLineReader.cpp b/base/common/ReplxxLineReader.cpp
index 7893e56d751..3d665744223 100644
--- a/base/common/ReplxxLineReader.cpp
+++ b/base/common/ReplxxLineReader.cpp
@@ -1,8 +1,9 @@
 #include <common/ReplxxLineReader.h>
 #include <common/errnoToString.h>
 
-#include <errno.h>
-#include <string.h>
+#include <chrono>
+#include <cerrno>
+#include <cstring>
 #include <unistd.h>
 #include <functional>
 #include <sys/file.h>
@@ -24,6 +25,91 @@ void trim(String & s)
     s.erase(std::find_if(s.rbegin(), s.rend(), [](int ch) { return !std::isspace(ch); }).base(), s.end());
 }
 
+/// Copied from replxx::src/util.cxx::now_ms_str()
+std::string replxx_now_ms_str()
+{
+    std::chrono::milliseconds ms(std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now().time_since_epoch()));
+    time_t t = ms.count() / 1000;
+    tm broken;
+    if (!localtime_r(&t, &broken))
+    {
+        return std::string();
+    }
+
+    static int const BUFF_SIZE(32);
+    char str[BUFF_SIZE];
+    strftime(str, BUFF_SIZE, "%Y-%m-%d %H:%M:%S.", &broken);
+    snprintf(str + sizeof("YYYY-mm-dd HH:MM:SS"), 5, "%03d", static_cast<int>(ms.count() % 1000));
+    return str;
+}
+
+/// Convert from readline to replxx format.
+///
+/// replxx requires each history line to prepended with time line:
+///
+///     ### YYYY-MM-DD HH:MM:SS.SSS
+///     select 1
+///
+/// And w/o those service lines it will load all lines from history file as
+/// one history line for suggestion. And if there are lots of lines in file it
+/// will take lots of time (getline() + tons of reallocations).
+///
+/// NOTE: this code uses std::ifstream/std::ofstream like original replxx code.
+void convertHistoryFile(const std::string & path, replxx::Replxx & rx)
+{
+    std::ifstream in(path);
+    if (!in)
+    {
+        rx.print("Cannot open %s reading (for conversion): %s\n",
+            path.c_str(), errnoToString(errno).c_str());
+        return;
+    }
+
+    std::string line;
+    if (!getline(in, line).good())
+    {
+        rx.print("Cannot read from %s (for conversion): %s\n",
+            path.c_str(), errnoToString(errno).c_str());
+        return;
+    }
+
+    /// This is the marker of the date, no need to convert.
+    static char const REPLXX_TIMESTAMP_PATTERN[] = "### dddd-dd-dd dd:dd:dd.ddd";
+    if (line.starts_with("### ") && line.size() == strlen(REPLXX_TIMESTAMP_PATTERN))
+    {
+        return;
+    }
+
+    std::vector<std::string> lines;
+    in.seekg(0);
+    while (getline(in, line).good())
+    {
+        lines.push_back(line);
+    }
+    in.close();
+
+    size_t lines_size = lines.size();
+    std::sort(lines.begin(), lines.end());
+    lines.erase(std::unique(lines.begin(), lines.end()), lines.end());
+    rx.print("The history file (%s) is in old format. %zu lines, %zu unique lines.\n",
+        path.c_str(), lines_size, lines.size());
+
+    std::ofstream out(path);
+    if (!out)
+    {
+        rx.print("Cannot open %s for writing (for conversion): %s\n",
+            path.c_str(), errnoToString(errno).c_str());
+        return;
+    }
+
+    const std::string & timestamp = replxx_now_ms_str();
+    for (const auto & out_line : lines)
+    {
+        out << "### " << timestamp << "\n" << out_line << std::endl;
+    }
+    out.close();
+}
+
 }
 
 ReplxxLineReader::ReplxxLineReader(
@@ -47,6 +133,8 @@ ReplxxLineReader::ReplxxLineReader(
         }
         else
         {
+            convertHistoryFile(history_file_path, rx);
+
             if (flock(history_file_fd, LOCK_SH))
             {
                 rx.print("Shared lock of history file failed: %s\n", errnoToString(errno).c_str());
diff --git a/tests/queries/0_stateless/01933_client_replxx_convert_history.expect b/tests/queries/0_stateless/01933_client_replxx_convert_history.expect
new file mode 100755
index 00000000000..890d024847f
--- /dev/null
+++ b/tests/queries/0_stateless/01933_client_replxx_convert_history.expect
@@ -0,0 +1,33 @@
+#!/usr/bin/expect -f
+
+log_user 0
+set timeout 60
+match_max 100000
+# A default timeout action is to do nothing, change it to fail
+expect_after {
+    timeout {
+        exit 1
+    }
+}
+set basedir [file dirname $argv0]
+
+exec bash -c "echo select 1 > $argv0.txt"
+exec bash -c "echo select 1 >> $argv0.txt"
+exec bash -c "echo select 1 >> $argv0.txt"
+
+spawn bash -c "source $basedir/../shell_config.sh ; \$CLICKHOUSE_CLIENT_BINARY \$CLICKHOUSE_CLIENT_OPT --history_file=$argv0.txt"
+expect "The history file ($argv0.txt) is in old format. 3 lines, 1 unique lines."
+expect ":) "
+send -- "\4"
+expect eof
+
+spawn bash -c "wc -l $argv0.txt"
+# The following lines are expected:
+#
+#     ### YYYY-MM-DD HH:MM:SS.SSS
+#     select 1
+#
+expect "2"
+expect eof
+
+exec bash -c "rm $argv0.txt"
diff --git a/tests/queries/0_stateless/01933_client_replxx_convert_history.reference b/tests/queries/0_stateless/01933_client_replxx_convert_history.reference
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/tests/queries/skip_list.json b/tests/queries/skip_list.json
index 7c1f998e91d..e55b79028e1 100644
--- a/tests/queries/skip_list.json
+++ b/tests/queries/skip_list.json
@@ -851,6 +851,7 @@
         "01913_replace_dictionary",
         "01914_exchange_dictionaries",
         "01915_create_or_replace_dictionary",
-        "01925_test_storage_merge_aliases"
+        "01925_test_storage_merge_aliases",
+        "01933_client_replxx_convert_history" /// Uses non unique history file
     ]
 }