diff --git a/controller/state.go b/controller/state.go
index 1443ffb11e345..db3779e3566e7 100644
--- a/controller/state.go
+++ b/controller/state.go
@@ -88,7 +88,8 @@ type comparisonResult struct {
 	diffNormalizer       diff.Normalizer
 	appSourceType        v1alpha1.ApplicationSourceType
 	// timings maps phases of comparison to the duration it took to complete (for statistical purposes)
-	timings map[string]time.Duration
+	timings        map[string]time.Duration
+	diffResultList *diff.DiffResultList
 }
 
 func (res *comparisonResult) GetSyncStatus() *v1alpha1.SyncStatus {
@@ -632,6 +633,7 @@ func (m *appStateManager) CompareAppState(app *v1alpha1.Application, project *ap
 		managedResources:     managedResources,
 		reconciliationResult: reconciliation,
 		diffNormalizer:       diffNormalizer,
+		diffResultList:       diffResults,
 	}
 	if manifestInfo != nil {
 		compRes.appSourceType = v1alpha1.ApplicationSourceType(manifestInfo.SourceType)
diff --git a/controller/sync.go b/controller/sync.go
index 33643b1e57c1c..6f975eda55634 100644
--- a/controller/sync.go
+++ b/controller/sync.go
@@ -135,6 +135,7 @@ func (m *appStateManager) SyncAppState(app *v1alpha1.Application, state *v1alpha
 			Order:       i + 1,
 		})
 	}
+
 	syncCtx, err := sync.NewSyncContext(
 		compareResult.syncStatus.Revision,
 		compareResult.reconciliationResult,
@@ -168,6 +169,7 @@ func (m *appStateManager) SyncAppState(app *v1alpha1.Application, state *v1alpha
 		}),
 		sync.WithSyncWaveHook(delayBetweenSyncWaves),
 		sync.WithPruneLast(syncOp.SyncOptions.HasOption("PruneLast=true")),
+		sync.WithResourceModificationChecker(syncOp.SyncOptions.HasOption("ApplyOutOfSyncOnly=true"), compareResult.diffResultList),
 	)
 
 	if err != nil {
diff --git a/docs/user-guide/selective_sync.md b/docs/user-guide/selective_sync.md
index 9e993cf285ad7..d607cc636b1a1 100644
--- a/docs/user-guide/selective_sync.md
+++ b/docs/user-guide/selective_sync.md
@@ -7,4 +7,11 @@ A *selective sync* is one where only some resources are sync'd. You can choose w
 When doing so, bear in mind:
 
 * Your sync is not recorded in the history, and so rollback is not possible.
-* Hooks are not run.
\ No newline at end of file
+* Hooks are not run.
+
+## Selective Sync Option
+
+>v1.8
+
+Turning on selective sync option which will sync only out-of-sync resources.
+See [sync options](sync-options.md#selective-sync) documentation for more details.
diff --git a/docs/user-guide/sync-options.md b/docs/user-guide/sync-options.md
index 45c5ddc1300f3..498dff31a2ffb 100644
--- a/docs/user-guide/sync-options.md
+++ b/docs/user-guide/sync-options.md
@@ -57,3 +57,31 @@ metadata:
 ```
 
 The dry run will still be executed if the CRD is already present in the cluster.
+
+## Selective Sync
+
+>v1.8
+
+Currently when syncing using auto sync ArgoCD applies every object in the application. 
+For applications containing thousands of objects this takes quite a long time and puts undue pressure on the api server.
+Turning on selective sync option which will sync only out-of-sync resources. 
+
+You can add this option by following ways
+
+1) Add `ApplyOutOfSync=true` in manifest
+
+Example:
+
+```yaml
+syncPolicy:
+  syncOptions:
+    - ApplyOutOfSyncOnly=true
+``` 
+
+2) Set sync option via argocd cli
+
+Example:
+
+```bash
+$ argocd app set guestbook --sync-option ApplyOutOfSyncOnly=true
+```
\ No newline at end of file
diff --git a/go.mod b/go.mod
index c349d8c014ab4..2c26870053106 100644
--- a/go.mod
+++ b/go.mod
@@ -7,7 +7,7 @@ require (
 	github.com/TomOnTime/utfutil v0.0.0-20180511104225-09c41003ee1d
 	github.com/alicebob/gopher-json v0.0.0-20180125190556-5a6b3ba71ee6 // indirect
 	github.com/alicebob/miniredis v2.5.0+incompatible
-	github.com/argoproj/gitops-engine v0.2.1-0.20210112204306-814d79df4954
+	github.com/argoproj/gitops-engine v0.2.1-0.20210129183711-c5b7114c501f
 	github.com/argoproj/pkg v0.2.0
 	github.com/bombsimon/logrusr v1.0.0
 	github.com/casbin/casbin v1.9.1
diff --git a/go.sum b/go.sum
index de04304522124..a973f44b32e0a 100644
--- a/go.sum
+++ b/go.sum
@@ -86,8 +86,8 @@ github.com/andreyvit/diff v0.0.0-20170406064948-c7f18ee00883/go.mod h1:rCTlJbsFo
 github.com/anmitsu/go-shlex v0.0.0-20161002113705-648efa622239 h1:kFOfPq6dUM1hTo4JG6LR5AXSUEsOjtdm0kw0FtQtMJA=
 github.com/anmitsu/go-shlex v0.0.0-20161002113705-648efa622239/go.mod h1:2FmKhYUyUczH0OGQWaF5ceTx0UBShxjsH6f8oGKYe2c=
 github.com/antihax/optional v1.0.0/go.mod h1:uupD/76wgC+ih3iEmQUL+0Ugr19nfwCT1kdvxnR2qWY=
-github.com/argoproj/gitops-engine v0.2.1-0.20210112204306-814d79df4954 h1:IJSkAuhE4DrLDJmGPa0eGCK20gjCQokkjk2Il7Pd/Sw=
-github.com/argoproj/gitops-engine v0.2.1-0.20210112204306-814d79df4954/go.mod h1:dmGvluybnmaSzsJA7PnrgCoSYQ5stFUNqS46F3gma+M=
+github.com/argoproj/gitops-engine v0.2.1-0.20210129183711-c5b7114c501f h1:QAf9m8jTw9TqRRNSBtygvZrrxWWUtF1F0qtVPrFogF8=
+github.com/argoproj/gitops-engine v0.2.1-0.20210129183711-c5b7114c501f/go.mod h1:dmGvluybnmaSzsJA7PnrgCoSYQ5stFUNqS46F3gma+M=
 github.com/argoproj/pkg v0.2.0 h1:ETgC600kr8WcAi3MEVY5sA1H7H/u1/IysYOobwsZ8No=
 github.com/argoproj/pkg v0.2.0/go.mod h1:F4TZgInLUEjzsWFB/BTJBsewoEy0ucnKSq6vmQiD/yc=
 github.com/armon/circbuf v0.0.0-20150827004946-bbbad097214e/go.mod h1:3U/XgcO3hCbHZ8TKRvWD2dDTCfh9M9ya+I9JpbB7O8o=