diff --git a/src/corelib/time/qdatetime.cpp b/src/corelib/time/qdatetime.cpp
index 1b727e1c222..b41edc97456 100644
--- a/src/corelib/time/qdatetime.cpp
+++ b/src/corelib/time/qdatetime.cpp
@@ -3141,7 +3141,7 @@ static inline Qt::TimeSpec getSpec(const QDateTimeData &d)
 /* True if we *can cheaply determine* that a and b use the same offset.
    If they use different offsets or it would be expensive to find out, false.
    Calls to toMSecsSinceEpoch() are expensive, for these purposes.
-   See QDateTime's comparison operators.
+   See QDateTime's comparison operators and areFarEnoughApart().
 */
 static inline bool usesSameOffset(const QDateTimeData &a, const QDateTimeData &b)
 {
@@ -3168,6 +3168,26 @@ static inline bool usesSameOffset(const QDateTimeData &a, const QDateTimeData &b
     Q_UNREACHABLE_RETURN(false);
 }
 
+/* Even datetimes with different offset can be ordered by their getMSecs()
+   provided the difference is bigger than the largest difference in offset we're
+   prepared to believe in. Technically, it may be possible to construct a zone
+   with an offset outside the range and get wrong results - but the answer to
+   someone doing that is that their contrived timezone and its consequences are
+   their own responsibility.
+
+   If two datetimes' millis lie within the offset range of one another, we can't
+   take any short-cuts, even if they're in the same zone, because there may be a
+   zone transition between them. (The full 32-hour difference would only arise
+   before 1845, for one date-time in The Philippines, the other in Alaska.)
+*/
+bool areFarEnoughApart(qint64 leftMillis, qint64 rightMillis)
+{
+    constexpr qint64 UtcOffsetMillisRange
+        = (QTimeZone::MaxUtcOffsetSecs - QTimeZone::MinUtcOffsetSecs) * MSECS_PER_SEC;
+    qint64 gap = 0;
+    return qSubOverflow(leftMillis, rightMillis, &gap) || qAbs(gap) > UtcOffsetMillisRange;
+}
+
 // Refresh the LocalTime or TimeZone validity and offset
 static void refreshZonedDateTime(QDateTimeData &d, const QTimeZone &zone,
                                  QDateTimePrivate::TransitionOptions resolve)
@@ -5194,8 +5214,10 @@ bool QDateTime::equals(const QDateTime &other) const
     if (!other.isValid())
         return false;
 
-    if (usesSameOffset(d, other.d))
-        return getMSecs(d) == getMSecs(other.d);
+    const qint64 thisMs = getMSecs(d);
+    const qint64 yourMs = getMSecs(other.d);
+    if (usesSameOffset(d, other.d) || areFarEnoughApart(thisMs, yourMs))
+        return thisMs == yourMs;
 
     // Convert to UTC and compare
     return toMSecsSinceEpoch() == other.toMSecsSinceEpoch();
@@ -5241,8 +5263,9 @@ Qt::weak_ordering compareThreeWay(const QDateTime &lhs, const QDateTime &rhs)
     if (!rhs.isValid())
         return Qt::weak_ordering::greater; // we know that lhs is valid here
 
-    if (usesSameOffset(lhs.d, rhs.d))
-        return Qt::compareThreeWay(getMSecs(lhs.d), getMSecs(rhs.d));
+    const qint64 lhms = getMSecs(lhs.d), rhms = getMSecs(rhs.d);
+    if (usesSameOffset(lhs.d, rhs.d) || areFarEnoughApart(lhms, rhms))
+        return Qt::compareThreeWay(lhms, rhms);
 
     // Convert to UTC and compare
     return Qt::compareThreeWay(lhs.toMSecsSinceEpoch(), rhs.toMSecsSinceEpoch());
diff --git a/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp b/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp
index 6975a4d9ced..5b8e35b963c 100644
--- a/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp
+++ b/tests/auto/corelib/time/qdatetime/tst_qdatetime.cpp
@@ -2537,6 +2537,31 @@ void tst_QDateTime::ordering_data()
     generateRow(epochEast1h, epochWest1h, Qt::weak_ordering::equivalent);
     if (epochTimeType == LocalTimeIsUtc)
         generateRow(epoch, local1970, Qt::weak_ordering::equivalent);
+
+#if QT_CONFIG(timezone)
+    // See qtimezone.h's comments on M(ax|in)UtcOffsetSecs:
+    QTimeZone alaska("America/Metlakatla"), phillip("Asia/Manila");
+    if (alaska.isValid() && phillip.isValid()) {
+        // Date Narciso Claveria ordered Manila's transition:
+        QDateTime edict(QDate(1844, 8, 16), QTime(8, 4), phillip); // GMT start of next day
+        // Backends may lack relevant data, so check:
+        const int alaskaOffset = edict.toTimeZone(alaska).offsetFromUtc();
+        const int manilaOffset = edict.toTimeZone(phillip).offsetFromUtc();
+        if (manilaOffset < 0 && alaskaOffset > 0) {
+            qint64 offsetGap = alaskaOffset - manilaOffset; // 31h 9m 42s
+            QDateTime equiv = edict.toTimeZone(alaska); // 15:13:42, on the next day.
+            QTest::newRow("extreme.equivalent")
+                << edict << equiv << Qt::weak_ordering::equivalent;
+            // Despite internal msecs values; edict's is offsetGap * 1000 less than equiv's.
+            // Even the least increase in that gap does imply less:
+            QTest::newRow("extreme.less")
+                << edict << equiv.addMSecs(1) << Qt::weak_ordering::less;
+            // Until offsetGap seconds later, edict's msecs doesn't catch up with equiv's:
+            QTest::newRow("extreme.greater")
+                << edict.addSecs(offsetGap - 1) << equiv << Qt::weak_ordering::greater;
+        }
+    }
+#endif
 }
 
 void tst_QDateTime::ordering()