diff --git a/pageserver/src/remote_storage.rs b/pageserver/src/remote_storage.rs
index aebd74af5a..8167830347 100644
--- a/pageserver/src/remote_storage.rs
+++ b/pageserver/src/remote_storage.rs
@@ -324,6 +324,9 @@ trait RemoteStorage: Send + Sync {
     async fn upload(
         &self,
         from: impl io::AsyncRead + Unpin + Send + Sync + 'static,
+        /// S3 PUT request requires the content length to be specified,
+        /// otherwise it starts to fail with the concurrent connection count increasing.
+        from_size_kb: usize,
         to: &Self::StoragePath,
         metadata: Option<StorageMetadata>,
     ) -> anyhow::Result<()>;
diff --git a/pageserver/src/remote_storage/local_fs.rs b/pageserver/src/remote_storage/local_fs.rs
index b40089d53c..15c69beebb 100644
--- a/pageserver/src/remote_storage/local_fs.rs
+++ b/pageserver/src/remote_storage/local_fs.rs
@@ -104,7 +104,8 @@ impl RemoteStorage for LocalFs {
 
     async fn upload(
         &self,
-        mut from: impl io::AsyncRead + Unpin + Send + Sync + 'static,
+        from: impl io::AsyncRead + Unpin + Send + Sync + 'static,
+        from_size_kb: usize,
         to: &Self::StoragePath,
         metadata: Option<StorageMetadata>,
     ) -> anyhow::Result<()> {
@@ -128,7 +129,7 @@ impl RemoteStorage for LocalFs {
                 })?,
         );
 
-        io::copy(&mut from, &mut destination)
+        io::copy(&mut from.take(from_size_kb as u64), &mut destination)
             .await
             .with_context(|| {
                 format!(
@@ -509,13 +510,13 @@ mod fs_tests {
         let repo_harness = RepoHarness::create("upload_file")?;
         let storage = create_storage()?;
 
-        let source = create_file_for_upload(
+        let (file, size) = create_file_for_upload(
             &storage.pageserver_workdir.join("whatever"),
             "whatever_contents",
         )
         .await?;
         let target_path = PathBuf::from("/").join("somewhere").join("else");
-        match storage.upload(source, &target_path, None).await {
+        match storage.upload(file, size, &target_path, None).await {
             Ok(()) => panic!("Should not allow storing files with wrong target path"),
             Err(e) => {
                 let message = format!("{:?}", e);
@@ -800,24 +801,17 @@ mod fs_tests {
         let timeline_path = harness.timeline_path(&TIMELINE_ID);
         let relative_timeline_path = timeline_path.strip_prefix(&harness.conf.workdir)?;
         let storage_path = storage.root.join(relative_timeline_path).join(name);
-        storage
-            .upload(
-                create_file_for_upload(
-                    &storage.pageserver_workdir.join(name),
-                    &dummy_contents(name),
-                )
-                .await?,
-                &storage_path,
-                metadata,
-            )
-            .await?;
+
+        let from_path = storage.pageserver_workdir.join(name);
+        let (file, size) = create_file_for_upload(&from_path, &dummy_contents(name)).await?;
+        storage.upload(file, size, &storage_path, metadata).await?;
         Ok(storage_path)
     }
 
     async fn create_file_for_upload(
         path: &Path,
         contents: &str,
-    ) -> anyhow::Result<io::BufReader<fs::File>> {
+    ) -> anyhow::Result<(io::BufReader<fs::File>, usize)> {
         std::fs::create_dir_all(path.parent().unwrap())?;
         let mut file_for_writing = std::fs::OpenOptions::new()
             .write(true)
@@ -825,8 +819,10 @@ mod fs_tests {
             .open(path)?;
         write!(file_for_writing, "{}", contents)?;
         drop(file_for_writing);
-        Ok(io::BufReader::new(
-            fs::OpenOptions::new().read(true).open(&path).await?,
+        let file_size = path.metadata()?.len() as usize;
+        Ok((
+            io::BufReader::new(fs::OpenOptions::new().read(true).open(&path).await?),
+            file_size,
         ))
     }
 
diff --git a/pageserver/src/remote_storage/s3_bucket.rs b/pageserver/src/remote_storage/s3_bucket.rs
index bfd28168f4..b99fa478c4 100644
--- a/pageserver/src/remote_storage/s3_bucket.rs
+++ b/pageserver/src/remote_storage/s3_bucket.rs
@@ -180,12 +180,16 @@ impl RemoteStorage for S3Bucket {
     async fn upload(
         &self,
         from: impl io::AsyncRead + Unpin + Send + Sync + 'static,
+        from_size_kb: usize,
         to: &Self::StoragePath,
         metadata: Option<StorageMetadata>,
     ) -> anyhow::Result<()> {
         self.client
             .put_object(PutObjectRequest {
-                body: Some(StreamingBody::new(ReaderStream::new(from))),
+                body: Some(StreamingBody::new_with_size(
+                    ReaderStream::new(from),
+                    from_size_kb,
+                )),
                 bucket: self.bucket_name.clone(),
                 key: to.key().to_owned(),
                 metadata: metadata.map(|m| m.0),