diff --git a/Source/Core/VideoBackends/D3D12/D3DTexture.cpp b/Source/Core/VideoBackends/D3D12/D3DTexture.cpp
index f913715e75..a3fe3b666e 100644
--- a/Source/Core/VideoBackends/D3D12/D3DTexture.cpp
+++ b/Source/Core/VideoBackends/D3D12/D3DTexture.cpp
@@ -21,6 +21,9 @@ namespace DX12
 namespace D3D
 {
 
+constexpr size_t INITIAL_TEXTURE_UPLOAD_BUFFER_SIZE = 4 * 1024 * 1024;
+constexpr size_t MAXIMUM_TEXTURE_UPLOAD_BUFFER_SIZE = 64 * 1024 * 1024;
+
 static std::unique_ptr<D3DStreamBuffer> s_texture_upload_stream_buffer;
 
 void CleanupPersistentD3DTextureResources()
@@ -32,16 +35,39 @@ void ReplaceRGBATexture2D(ID3D12Resource* texture12, const u8* buffer, unsigned
 {
 	const unsigned int upload_size = AlignValue(src_pitch, D3D12_TEXTURE_DATA_PITCH_ALIGNMENT) * height;
 
-	if (!s_texture_upload_stream_buffer)
-	{
-		s_texture_upload_stream_buffer = std::make_unique<D3DStreamBuffer>(4 * 1024 * 1024, 64 * 1024 * 1024, nullptr);
-	}
+	ID3D12Resource* upload_buffer = nullptr;
+	size_t upload_buffer_offset = 0;
+	u8* dest_data = nullptr;
 
-	bool current_command_list_executed = s_texture_upload_stream_buffer->AllocateSpaceInBuffer(upload_size, D3D12_TEXTURE_DATA_PLACEMENT_ALIGNMENT);
-	if (current_command_list_executed)
+	if (upload_size > MAXIMUM_TEXTURE_UPLOAD_BUFFER_SIZE)
 	{
-		g_renderer->SetViewport();
-		D3D::current_command_list->OMSetRenderTargets(1, &FramebufferManager::GetEFBColorTexture()->GetRTV12(), FALSE, &FramebufferManager::GetEFBDepthTexture()->GetDSV12());
+		// If the texture is too large to fit in the upload buffer, create a temporary buffer instead.
+		// This will only be the case for large (e.g. 8192x8192) textures from custom texture packs.
+		CheckHR(D3D::device12->CreateCommittedResource(
+			&CD3DX12_HEAP_PROPERTIES(D3D12_HEAP_TYPE_UPLOAD),
+			D3D12_HEAP_FLAG_NONE,
+			&CD3DX12_RESOURCE_DESC::Buffer(upload_size),
+			D3D12_RESOURCE_STATE_GENERIC_READ,
+			nullptr,
+			IID_PPV_ARGS(&upload_buffer)));
+
+		CheckHR(upload_buffer->Map(0, nullptr, reinterpret_cast<void**>(&dest_data)));
+	}
+	else
+	{
+		if (!s_texture_upload_stream_buffer)
+			s_texture_upload_stream_buffer = std::make_unique<D3DStreamBuffer>(INITIAL_TEXTURE_UPLOAD_BUFFER_SIZE, MAXIMUM_TEXTURE_UPLOAD_BUFFER_SIZE, nullptr);
+
+		bool current_command_list_executed = s_texture_upload_stream_buffer->AllocateSpaceInBuffer(upload_size, D3D12_TEXTURE_DATA_PLACEMENT_ALIGNMENT);
+		if (current_command_list_executed)
+		{
+			g_renderer->SetViewport();
+			D3D::current_command_list->OMSetRenderTargets(1, &FramebufferManager::GetEFBColorTexture()->GetRTV12(), FALSE, &FramebufferManager::GetEFBDepthTexture()->GetDSV12());
+		}
+
+		upload_buffer = s_texture_upload_stream_buffer->GetBuffer();
+		upload_buffer_offset = s_texture_upload_stream_buffer->GetOffsetOfCurrentAllocation();
+		dest_data = reinterpret_cast<u8*>(s_texture_upload_stream_buffer->GetCPUAddressOfCurrentAllocation());
 	}
 
 	ResourceBarrier(current_command_list, texture12, current_resource_state, D3D12_RESOURCE_STATE_COPY_DEST, level);
@@ -51,9 +77,8 @@ void ReplaceRGBATexture2D(ID3D12Resource* texture12, const u8* buffer, unsigned
 	u64 upload_row_size_in_bytes = 0;
 	u64 upload_total_bytes = 0;
 
-	D3D::device12->GetCopyableFootprints(&texture12->GetDesc(), level, 1, s_texture_upload_stream_buffer->GetOffsetOfCurrentAllocation(), &upload_footprint, &upload_rows, &upload_row_size_in_bytes, &upload_total_bytes);
+	D3D::device12->GetCopyableFootprints(&texture12->GetDesc(), level, 1, upload_buffer_offset, &upload_footprint, &upload_rows, &upload_row_size_in_bytes, &upload_total_bytes);
 
-	u8* dest_data = reinterpret_cast<u8*>(s_texture_upload_stream_buffer->GetCPUAddressOfCurrentAllocation());
 	const u8* src_data = reinterpret_cast<const u8*>(buffer);
 	for (u32 y = 0; y < upload_rows; ++y)
 	{
@@ -64,9 +89,18 @@ void ReplaceRGBATexture2D(ID3D12Resource* texture12, const u8* buffer, unsigned
 			);
 	}
 
-	D3D::current_command_list->CopyTextureRegion(&CD3DX12_TEXTURE_COPY_LOCATION(texture12, level), 0, 0, 0, &CD3DX12_TEXTURE_COPY_LOCATION(s_texture_upload_stream_buffer->GetBuffer(), upload_footprint), nullptr);
+	D3D::current_command_list->CopyTextureRegion(&CD3DX12_TEXTURE_COPY_LOCATION(texture12, level), 0, 0, 0, &CD3DX12_TEXTURE_COPY_LOCATION(upload_buffer, upload_footprint), nullptr);
 
 	ResourceBarrier(D3D::current_command_list, texture12, D3D12_RESOURCE_STATE_COPY_DEST, current_resource_state, level);
+
+	// Release temporary buffer after commands complete.
+	// We block here because otherwise if there was a large number of texture uploads, we may run out of memory.
+	if (!s_texture_upload_stream_buffer || upload_buffer != s_texture_upload_stream_buffer->GetBuffer())
+	{
+		D3D::command_list_mgr->ExecuteQueuedWork(true);
+		upload_buffer->Unmap(0, nullptr);
+		upload_buffer->Release();
+	}
 }
 
 }  // namespace