diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9ab1832b..29bc8f31 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 * New datastore option to ignore Redis cache when downloading media served by a `publicBaseUrl`. This can help ensure more requests get redirected to the CDN.
 * `HEAD /download` is now supported, as per [MSC4120](https://github.com/matrix-org/matrix-spec-proposals/pull/4120).
 * S3 datastores can now specify a `prefixLength` to improve S3 performance on some providers. See `config.sample.yaml` for details.
+* Add `multipartUploads` flag for running MMR against unsupported S3 providers. See `config.sample.yaml` for details. 
 
 ### Fixed
 
diff --git a/config.sample.yaml b/config.sample.yaml
index b46f2946..f87eef79 100644
--- a/config.sample.yaml
+++ b/config.sample.yaml
@@ -216,6 +216,12 @@ datastores:
       # help improve download speeds in some S3 providers. Should not be set to higher than
       # 16 to avoid future incompatibilities with MMR. Defaults to zero (no prefix).
       #prefixLength: 3
+      # Set to false to disable multipart uploads. This may be required for some *unsupported*
+      # S3 providers. Note that performance may be significantly degraded with this option set
+      # to false - installations with multipart uploads disabled will not receive support,
+      # particularly for performance concerns. If you are using AWS, DigitalOcean Spaces, or
+      # MinIO, you do not need to set or change this option - your environment is supported.
+      #multipartUploads: true
 
 # Options for controlling archives. Archives are exports of a particular user's content for
 # the purpose of GDPR or moving media to a different server.
diff --git a/datastores/s3.go b/datastores/s3.go
index 1e4e6b56..99f15ae3 100644
--- a/datastores/s3.go
+++ b/datastores/s3.go
@@ -23,6 +23,7 @@ type s3 struct {
 	publicBaseUrl      string
 	redirectWhenCached bool
 	prefixLength       int
+	multipartUploads   bool
 }
 
 func ResetS3Clients() {
@@ -44,6 +45,7 @@ func getS3(ds config.DatastoreConfig) (*s3, error) {
 	publicBaseUrl := ds.Options["publicBaseUrl"]
 	redirectWhenCachedStr, hasRedirectWhenCached := ds.Options["redirectWhenCached"]
 	prefixLengthStr, hasPrefixLength := ds.Options["prefixLength"]
+	useMultipartStr, hasMultipart := ds.Options["multipartUploads"]
 
 	if !hasStorageClass {
 		storageClass = "STANDARD"
@@ -54,6 +56,11 @@ func getS3(ds config.DatastoreConfig) (*s3, error) {
 		useSsl, _ = strconv.ParseBool(useSslStr)
 	}
 
+	useMultipart := true
+	if hasMultipart && useMultipartStr != "" {
+		useMultipart, _ = strconv.ParseBool(useMultipartStr)
+	}
+
 	redirectWhenCached := false
 	if hasRedirectWhenCached && redirectWhenCachedStr != "" {
 		redirectWhenCached, _ = strconv.ParseBool(redirectWhenCachedStr)
@@ -88,6 +95,7 @@ func getS3(ds config.DatastoreConfig) (*s3, error) {
 		publicBaseUrl:      publicBaseUrl,
 		redirectWhenCached: redirectWhenCached,
 		prefixLength:       prefixLength,
+		multipartUploads:   useMultipart,
 	}
 	s3clients.Store(ds.Id, s3c)
 	return s3c, nil
diff --git a/datastores/upload.go b/datastores/upload.go
index 39e403da..d365deea 100644
--- a/datastores/upload.go
+++ b/datastores/upload.go
@@ -44,7 +44,11 @@ func Upload(ctx rcontext.RequestContext, ds config.DatastoreConfig, data io.Read
 
 		metrics.S3Operations.With(prometheus.Labels{"operation": "PutObject"}).Inc()
 		var info minio.UploadInfo
-		info, err = s3c.client.PutObject(ctx.Context, s3c.bucket, objectName, tee, size, minio.PutObjectOptions{StorageClass: s3c.storageClass, ContentType: contentType})
+		info, err = s3c.client.PutObject(ctx.Context, s3c.bucket, objectName, tee, size, minio.PutObjectOptions{
+			StorageClass:     s3c.storageClass,
+			ContentType:      contentType,
+			DisableMultipart: !s3c.multipartUploads,
+		})
 		uploadedBytes = info.Size
 	} else if ds.Type == "file" {
 		basePath := ds.Options["path"]