diff --git a/quic/core/quic_connection_test.cc b/quic/core/quic_connection_test.cc
index 0716425..7506c17 100644
--- a/quic/core/quic_connection_test.cc
+++ b/quic/core/quic_connection_test.cc
@@ -3379,12 +3379,6 @@
   // Ensure that the data is still in flight, but the retransmission alarm is no
   // longer set.
   EXPECT_GT(manager_->GetBytesInFlight(), 0u);
-  if (GetQuicReloadableFlag(quic_optimize_inflight_check)) {
-    EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
-    // Firing the alarm should remove all bytes_in_flight.
-    connection_.GetRetransmissionAlarm()->Fire();
-    EXPECT_EQ(0u, manager_->GetBytesInFlight());
-  }
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());
 }
 
@@ -3628,13 +3622,6 @@
 
   writer_->SetWritable();
   connection_.OnCanWrite();
-  // There is now a pending packet, but with no retransmittable frames.
-  if (GetQuicReloadableFlag(quic_optimize_inflight_check)) {
-    EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());
-    // Firing the alarm should remove all bytes_in_flight.
-    connection_.GetRetransmissionAlarm()->Fire();
-    EXPECT_EQ(0u, manager_->GetBytesInFlight());
-  }
   EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());
   EXPECT_FALSE(QuicConnectionPeer::HasRetransmittableFrames(&connection_, 2));
 }
diff --git a/quic/core/quic_sent_packet_manager.cc b/quic/core/quic_sent_packet_manager.cc
index ca5c7f5..a4aa08e 100644
--- a/quic/core/quic_sent_packet_manager.cc
+++ b/quic/core/quic_sent_packet_manager.cc
@@ -756,13 +756,6 @@
     return false;
   }
   if (!MaybeRetransmitOldestPacket(TLP_RETRANSMISSION)) {
-    // If no tail loss probe can be sent, because there are no retransmittable
-    // packets, execute a conventional RTO to abandon old packets.
-    if (GetQuicReloadableFlag(quic_optimize_inflight_check)) {
-      QUIC_RELOADABLE_FLAG_COUNT(quic_optimize_inflight_check);
-      pending_timer_transmission_count_ = 0;
-      RetransmitRtoPackets();
-    }
     return false;
   }
   return true;
@@ -845,8 +838,7 @@
     return LOSS_MODE;
   }
   if (consecutive_tlp_count_ < max_tail_loss_probes_) {
-    if (GetQuicReloadableFlag(quic_optimize_inflight_check) ||
-        unacked_packets_.HasUnackedRetransmittableFrames()) {
+    if (unacked_packets_.HasUnackedRetransmittableFrames()) {
       return TLP_MODE;
     }
   }
@@ -928,8 +920,7 @@
       pending_timer_transmission_count_ > 0) {
     return QuicTime::Zero();
   }
-  if (!GetQuicReloadableFlag(quic_optimize_inflight_check) &&
-      !unacked_packets_.HasUnackedRetransmittableFrames()) {
+  if (!unacked_packets_.HasUnackedRetransmittableFrames()) {
     return QuicTime::Zero();
   }
   switch (GetRetransmissionMode()) {
diff --git a/quic/core/quic_unacked_packet_map.cc b/quic/core/quic_unacked_packet_map.cc
index 2923ae1..f07fd31 100644
--- a/quic/core/quic_unacked_packet_map.cc
+++ b/quic/core/quic_unacked_packet_map.cc
@@ -376,7 +376,6 @@
 }
 
 bool QuicUnackedPacketMap::HasUnackedRetransmittableFrames() const {
-  DCHECK(!GetQuicReloadableFlag(quic_optimize_inflight_check));
   for (auto it = unacked_packets_.rbegin(); it != unacked_packets_.rend();
        ++it) {
     if (it->in_flight && HasRetransmittableFrames(*it)) {
diff --git a/quic/core/quic_unacked_packet_map_test.cc b/quic/core/quic_unacked_packet_map_test.cc
index fdec7a6..807a959 100644
--- a/quic/core/quic_unacked_packet_map_test.cc
+++ b/quic/core/quic_unacked_packet_map_test.cc
@@ -125,9 +125,7 @@
     unacked_packets_.RemoveObsoletePackets();
     if (num_packets == 0) {
       EXPECT_TRUE(unacked_packets_.empty());
-      if (!GetQuicReloadableFlag(quic_optimize_inflight_check)) {
-        EXPECT_FALSE(unacked_packets_.HasUnackedRetransmittableFrames());
-      }
+      EXPECT_FALSE(unacked_packets_.HasUnackedRetransmittableFrames());
       return;
     }
     EXPECT_FALSE(unacked_packets_.empty());
diff --git a/quic/quartc/quartc_factory.cc b/quic/quartc/quartc_factory.cc
index dab1a31..0c11bd0 100644
--- a/quic/quartc/quartc_factory.cc
+++ b/quic/quartc/quartc_factory.cc
@@ -51,11 +51,6 @@
 }
 
 void ConfigureGlobalQuicSettings() {
-  // TODO(b/134054062): quic_optimize_inflight_check is incompatible with
-  // datagram/message-only flows.  Remove this if/when the optimization is
-  // fixed.
-  SetQuicReloadableFlag(quic_optimize_inflight_check, false);
-
   // Fixes behavior of StopReading() with level-triggered stream sequencers.
   SetQuicReloadableFlag(quic_stop_reading_when_level_triggered, true);