diff --git a/pkg/enqueuer/enqueuer.go b/pkg/enqueuer/enqueuer.go
index 06c1664c91..bfd5f6e73f 100644
--- a/pkg/enqueuer/enqueuer.go
+++ b/pkg/enqueuer/enqueuer.go
@@ -56,9 +56,10 @@ type ItemList struct {
 }
 
 type S3Lister struct {
-	S3Paths  []string `json:"s3_paths"` // s3://<bucket_name>/key
-	Includes []string `json:"includes"`
-	Excludes []string `json:"excludes"`
+	S3Paths    []string `json:"s3_paths"` // s3://<bucket_name>/key
+	Includes   []string `json:"includes"`
+	Excludes   []string `json:"excludes"`
+	MaxResults *int64   `json:"-"` // this is not currently exposed to the user (it's used for validations)
 }
 
 type FilePathLister struct {
@@ -246,7 +247,7 @@ func (e *Enqueuer) enqueueS3Paths(s3PathsLister *FilePathLister) (int, error) {
 	var s3PathList []string
 	uploader := newSQSBatchUploader(e.envConfig.APIName, e.envConfig.JobID, e.queueURL, e.aws.SQS())
 
-	err := s3IteratorFromLister(e.aws, s3PathsLister.S3Lister, func(bucket string, s3Obj *s3.Object) (bool, error) {
+	_, err := s3IteratorFromLister(e.aws, s3PathsLister.S3Lister, func(bucket string, s3Obj *s3.Object) (bool, error) {
 		s3Path := awslib.S3Path(bucket, *s3Obj.Key)
 
 		s3PathList = append(s3PathList, s3Path)
@@ -290,7 +291,7 @@ func (e *Enqueuer) enqueueS3FileContents(delimitedFiles *DelimitedFiles) (int, e
 	uploader := newSQSBatchUploader(e.envConfig.APIName, e.envConfig.JobID, e.queueURL, e.aws.SQS())
 
 	bytesBuffer := bytes.NewBuffer([]byte{})
-	err := s3IteratorFromLister(e.aws, delimitedFiles.S3Lister, func(bucket string, s3Obj *s3.Object) (bool, error) {
+	_, err := s3IteratorFromLister(e.aws, delimitedFiles.S3Lister, func(bucket string, s3Obj *s3.Object) (bool, error) {
 		s3Path := awslib.S3Path(bucket, *s3Obj.Key)
 		log.Info("enqueuing contents from file", zap.String("path", s3Path))
 
diff --git a/pkg/enqueuer/helpers.go b/pkg/enqueuer/helpers.go
index d7c2246852..a8df5d43d6 100644
--- a/pkg/enqueuer/helpers.go
+++ b/pkg/enqueuer/helpers.go
@@ -64,13 +64,13 @@ func addJSONObjectsToQueue(uploader *sqsBatchUploader, jsonMessageList *jsonBuff
 	return nil
 }
 
-func s3IteratorFromLister(awsClient *awslib.Client, s3Lister S3Lister, fn func(string, *s3.Object) (bool, error)) error {
+func s3IteratorFromLister(awsClient *awslib.Client, s3Lister S3Lister, fn func(string, *s3.Object) (bool, error)) (int64, error) {
 	includeGlobPatterns := make([]glob.Glob, 0, len(s3Lister.Includes))
 
 	for _, includePattern := range s3Lister.Includes {
 		globExpression, err := glob.Compile(includePattern, '/')
 		if err != nil {
-			return errors.Wrap(err, "failed to interpret glob pattern", includePattern)
+			return 0, errors.Wrap(err, "failed to interpret glob pattern", includePattern)
 		}
 		includeGlobPatterns = append(includeGlobPatterns, globExpression)
 	}
@@ -79,20 +79,22 @@ func s3IteratorFromLister(awsClient *awslib.Client, s3Lister S3Lister, fn func(s
 	for _, excludePattern := range s3Lister.Excludes {
 		globExpression, err := glob.Compile(excludePattern, '/')
 		if err != nil {
-			return errors.Wrap(err, "failed to interpret glob pattern", excludePattern)
+			return 0, errors.Wrap(err, "failed to interpret glob pattern", excludePattern)
 		}
 		excludeGlobPatterns = append(excludeGlobPatterns, globExpression)
 	}
 
+	var numResults int64
+
 	for _, s3Path := range s3Lister.S3Paths {
 		bucket, key, err := awslib.SplitS3Path(s3Path)
 		if err != nil {
-			return err
+			return 0, err
 		}
 
 		awsClientForBucket, err := awslib.NewFromClientS3Path(s3Path, awsClient)
 		if err != nil {
-			return err
+			return 0, err
 		}
 
 		err = awsClientForBucket.S3Iterator(bucket, key, false, nil, nil, func(s3Obj *s3.Object) (bool, error) {
@@ -117,15 +119,24 @@ func s3IteratorFromLister(awsClient *awslib.Client, s3Lister S3Lister, fn func(s
 			}
 
 			if !shouldSkip {
-				return fn(bucket, s3Obj)
+				shouldContinue, err := fn(bucket, s3Obj)
+				numResults++
+				if s3Lister.MaxResults != nil && numResults >= *s3Lister.MaxResults {
+					shouldContinue = false
+				}
+				return shouldContinue, err
 			}
 
 			return true, nil
 		})
 		if err != nil {
-			return err
+			return 0, err
+		}
+
+		if s3Lister.MaxResults != nil && numResults >= *s3Lister.MaxResults {
+			return numResults, nil
 		}
 	}
 
-	return nil
+	return numResults, nil
 }
diff --git a/pkg/operator/resources/job/batchapi/s3_iterator.go b/pkg/operator/resources/job/batchapi/s3_iterator.go
index 80848f32c2..2860c27c5b 100644
--- a/pkg/operator/resources/job/batchapi/s3_iterator.go
+++ b/pkg/operator/resources/job/batchapi/s3_iterator.go
@@ -26,13 +26,13 @@ import (
 )
 
 // Takes in a function(shouldSkip, bucketName, s3.Object)
-func s3IteratorFromLister(s3Lister schema.S3Lister, fn func(string, *s3.Object) (bool, error)) error {
+func s3IteratorFromLister(s3Lister schema.S3Lister, fn func(string, *s3.Object) (bool, error)) (int64, error) {
 	includeGlobPatterns := make([]glob.Glob, 0, len(s3Lister.Includes))
 
 	for _, includePattern := range s3Lister.Includes {
 		globExpression, err := glob.Compile(includePattern, '/')
 		if err != nil {
-			return errors.Wrap(err, "failed to interpret glob pattern", includePattern)
+			return 0, errors.Wrap(err, "failed to interpret glob pattern", includePattern)
 		}
 		includeGlobPatterns = append(includeGlobPatterns, globExpression)
 	}
@@ -41,20 +41,22 @@ func s3IteratorFromLister(s3Lister schema.S3Lister, fn func(string, *s3.Object)
 	for _, excludePattern := range s3Lister.Excludes {
 		globExpression, err := glob.Compile(excludePattern, '/')
 		if err != nil {
-			return errors.Wrap(err, "failed to interpret glob pattern", excludePattern)
+			return 0, errors.Wrap(err, "failed to interpret glob pattern", excludePattern)
 		}
 		excludeGlobPatterns = append(excludeGlobPatterns, globExpression)
 	}
 
+	var numResults int64
+
 	for _, s3Path := range s3Lister.S3Paths {
 		bucket, key, err := aws.SplitS3Path(s3Path)
 		if err != nil {
-			return err
+			return 0, err
 		}
 
 		awsClientForBucket, err := aws.NewFromClientS3Path(s3Path, config.AWS)
 		if err != nil {
-			return err
+			return 0, err
 		}
 
 		err = awsClientForBucket.S3Iterator(bucket, key, false, nil, nil, func(s3Obj *s3.Object) (bool, error) {
@@ -79,15 +81,24 @@ func s3IteratorFromLister(s3Lister schema.S3Lister, fn func(string, *s3.Object)
 			}
 
 			if !shouldSkip {
-				return fn(bucket, s3Obj)
+				shouldContinue, err := fn(bucket, s3Obj)
+				numResults++
+				if s3Lister.MaxResults != nil && numResults >= *s3Lister.MaxResults {
+					shouldContinue = false
+				}
+				return shouldContinue, err
 			}
 
 			return true, nil
 		})
 		if err != nil {
-			return err
+			return 0, err
+		}
+
+		if s3Lister.MaxResults != nil && numResults >= *s3Lister.MaxResults {
+			return numResults, nil
 		}
 	}
 
-	return nil
+	return numResults, nil
 }
diff --git a/pkg/operator/resources/job/batchapi/validations.go b/pkg/operator/resources/job/batchapi/validations.go
index fe51cd8d27..c28439491a 100644
--- a/pkg/operator/resources/job/batchapi/validations.go
+++ b/pkg/operator/resources/job/batchapi/validations.go
@@ -24,6 +24,7 @@ import (
 	awslib "github.com/cortexlabs/cortex/pkg/lib/aws"
 	cr "github.com/cortexlabs/cortex/pkg/lib/configreader"
 	"github.com/cortexlabs/cortex/pkg/lib/errors"
+	"github.com/cortexlabs/cortex/pkg/lib/pointer"
 	"github.com/cortexlabs/cortex/pkg/operator/resources/job"
 	"github.com/cortexlabs/cortex/pkg/operator/schema"
 	"github.com/gobwas/glob"
@@ -143,26 +144,30 @@ func validateS3Lister(s3Lister *schema.S3Lister) error {
 		}
 	}
 
-	filesFound := 0
 	for _, s3Path := range s3Lister.S3Paths {
 		if !awslib.IsValidS3Path(s3Path) {
 			return awslib.ErrorInvalidS3Path(s3Path)
 		}
+	}
 
-		err := s3IteratorFromLister(*s3Lister, func(objPath string, s3Obj *s3.Object) (bool, error) {
-			filesFound++
-			return false, nil
-		})
-		if err != nil {
-			return errors.Wrap(err, s3Path)
-		}
+	shortCircuitLister := schema.S3Lister{
+		S3Paths:    s3Lister.S3Paths,
+		Includes:   s3Lister.Includes,
+		Excludes:   s3Lister.Excludes,
+		MaxResults: pointer.Int64(1),
+	}
+	numResults, err := s3IteratorFromLister(shortCircuitLister, func(objPath string, s3Obj *s3.Object) (bool, error) {
+		return false, nil
+	})
+	if err != nil {
+		return err
+	}
 
-		if filesFound > 0 {
-			return nil
-		}
+	if numResults == 0 {
+		return ErrorNoS3FilesFound()
 	}
 
-	return ErrorNoS3FilesFound()
+	return nil
 }
 
 func listFilesDryRun(s3Lister *schema.S3Lister) ([]string, error) {
@@ -171,15 +176,14 @@ func listFilesDryRun(s3Lister *schema.S3Lister) ([]string, error) {
 		if !awslib.IsValidS3Path(s3Path) {
 			return nil, awslib.ErrorInvalidS3Path(s3Path)
 		}
+	}
 
-		err := s3IteratorFromLister(*s3Lister, func(bucket string, s3Obj *s3.Object) (bool, error) {
-			s3Files = append(s3Files, awslib.S3Path(bucket, *s3Obj.Key))
-			return true, nil
-		})
-
-		if err != nil {
-			return nil, errors.Wrap(err, s3Path)
-		}
+	_, err := s3IteratorFromLister(*s3Lister, func(bucket string, s3Obj *s3.Object) (bool, error) {
+		s3Files = append(s3Files, awslib.S3Path(bucket, *s3Obj.Key))
+		return true, nil
+	})
+	if err != nil {
+		return nil, err
 	}
 
 	if len(s3Files) == 0 {
diff --git a/pkg/operator/schema/job_submission.go b/pkg/operator/schema/job_submission.go
index 7fadf3b163..ad51932a20 100644
--- a/pkg/operator/schema/job_submission.go
+++ b/pkg/operator/schema/job_submission.go
@@ -28,9 +28,10 @@ type ItemList struct {
 }
 
 type S3Lister struct {
-	S3Paths  []string `json:"s3_paths"` // s3://<bucket_name>/key
-	Includes []string `json:"includes"`
-	Excludes []string `json:"excludes"`
+	S3Paths    []string `json:"s3_paths"` // s3://<bucket_name>/key
+	Includes   []string `json:"includes"`
+	Excludes   []string `json:"excludes"`
+	MaxResults *int64   `json:"-"` // this is not currently exposed to the user (it's used for validations)
 }
 
 type FilePathLister struct {