diff --git a/src/corelib/global/qcompilerdetection.h b/src/corelib/global/qcompilerdetection.h
index 9c46ea0efbc..0230b5a7844 100644
--- a/src/corelib/global/qcompilerdetection.h
+++ b/src/corelib/global/qcompilerdetection.h
@@ -857,6 +857,8 @@
 #    if _MSC_VER < 1936
 #      define Q_COMPILER_LACKS_THREE_WAY_COMPARE_SYMMETRY
 #    endif
+// QTBUG-124376: MSVC is slow at compiling qstrnlen()
+#    define Q_COMPILER_SLOW_QSTRNLEN_COMPILATION
 #  endif /* __cplusplus */
 #endif // defined(Q_CC_MSVC) && !defined(Q_CC_CLANG)
 
diff --git a/src/corelib/text/qstringalgorithms.h b/src/corelib/text/qstringalgorithms.h
index 3b9d8f3ccaf..41c607b857e 100644
--- a/src/corelib/text/qstringalgorithms.h
+++ b/src/corelib/text/qstringalgorithms.h
@@ -174,12 +174,21 @@ lengthHelperContainer(const Char (&str)[N])
     return lengthHelperContainerLoop(str);
 }
 
+inline qsizetype qstrnlen_helper(const char *str, size_t maxlen)
+{
+#if !defined(Q_COMPILER_SLOW_QSTRNLEN_COMPILATION)
+    return qstrnlen(str, maxlen);
+#else
+    return strnlen_s(str, maxlen);
+#endif
+}
+
 template <typename Char, size_t N> [[nodiscard]] constexpr inline
 std::enable_if_t<sizeof(Char) == 1, qsizetype> lengthHelperContainer(const Char (&str)[N])
 {
 #ifdef QT_SUPPORTS_IS_CONSTANT_EVALUATED
     if (!q20::is_constant_evaluated())
-        return qstrnlen(reinterpret_cast<const char *>(str), N);
+        return qstrnlen_helper(reinterpret_cast<const char *>(str), N);
 #endif
 
     return lengthHelperContainerLoop(str);