diff --git a/runtime/vm/heap/heap.cc b/runtime/vm/heap/heap.cc
index 42cd82c03d9..32053fcaefd 100644
--- a/runtime/vm/heap/heap.cc
+++ b/runtime/vm/heap/heap.cc
@@ -616,12 +616,17 @@ void Heap::CheckConcurrentMarking(Thread* thread,
   switch (phase) {
     case PageSpace::kMarking:
       if (mode_ != Dart_PerformanceMode_Latency) {
-        old_space_.IncrementalMarkWithSizeBudget(size);
+        // Back pressure: do slightly more marking work than allocation work.
+        old_space_.IncrementalMarkWithSizeBudget(size + (size >> 2));
       }
       return;
     case PageSpace::kSweepingLarge:
     case PageSpace::kSweepingRegular:
-      return;  // Busy.
+      if (mode_ != Dart_PerformanceMode_Latency) {
+        // Back pressure: do some sweeping work.
+        old_space_.IncrementalSweepWithSizeBudget(size);
+      }
+      return;
     case PageSpace::kAwaitingFinalization:
       CollectOldSpaceGarbage(thread, GCType::kMarkSweep, GCReason::kFinalize);
       return;
diff --git a/runtime/vm/heap/pages.cc b/runtime/vm/heap/pages.cc
index dedd1671dfd..40ad4f965c4 100644
--- a/runtime/vm/heap/pages.cc
+++ b/runtime/vm/heap/pages.cc
@@ -899,6 +899,13 @@ void PageSpace::IncrementalMarkWithTimeBudget(int64_t deadline) {
   }
 }
 
+void PageSpace::IncrementalSweepWithSizeBudget(intptr_t size) {
+  if (size >= kAllocatablePageSize) {
+    // Sweeping work is less divisible than marking work.
+    Sweep(/*exclusive=*/false, /*one_page=*/true);
+  }
+}
+
 void PageSpace::AssistTasks(MonitorLocker* ml) {
   if (phase() == PageSpace::kMarking) {
     ml->Exit();
@@ -1390,7 +1397,7 @@ void PageSpace::SweepLarge() {
   }
 }
 
-void PageSpace::Sweep(bool exclusive) {
+void PageSpace::Sweep(bool exclusive, bool one_page) {
   TIMELINE_FUNCTION_GC_DURATION(Thread::Current(), "Sweep");
 
   GCSweeper sweeper;
@@ -1436,6 +1443,8 @@ void PageSpace::Sweep(bool exclusive) {
     } else {
       IncreaseCapacityInWordsLocked(-(size >> kWordSizeLog2));
     }
+
+    if (one_page) break;
   }
 
   if (exclusive) {
diff --git a/runtime/vm/heap/pages.h b/runtime/vm/heap/pages.h
index 970a4c9c2fe..e18f8adbc62 100644
--- a/runtime/vm/heap/pages.h
+++ b/runtime/vm/heap/pages.h
@@ -259,6 +259,7 @@ class PageSpace {
   bool ShouldPerformIdleMarkCompact(int64_t deadline);
   void IncrementalMarkWithSizeBudget(intptr_t size);
   void IncrementalMarkWithTimeBudget(int64_t deadline);
+  void IncrementalSweepWithSizeBudget(intptr_t size);
   void AssistTasks(MonitorLocker* ml);
 
   void AddGCTime(int64_t micros) { gc_time_micros_ += micros; }
@@ -426,7 +427,7 @@ class PageSpace {
   void SweepExecutable();
   void SweepNew();
   void SweepLarge();
-  void Sweep(bool exclusive);
+  void Sweep(bool exclusive, bool one_page = false);
   void ConcurrentSweep(IsolateGroup* isolate_group);
   void Compact(Thread* thread);