autoload/lsp/diag.vim      | 7 ++++++-
 autoload/lsp/lsp.vim       | 6 ++++++
 autoload/lsp/lspserver.vim | 2 ++
 doc/lsp.txt                | 7 +++++++

diff --git a/autoload/lsp/diag.vim b/autoload/lsp/diag.vim
index f812c401aaf0e89cd44b82c37bb6df22b10479b3..cf74879b0484c84e57ce3fc88eea69c78e8819d2 100644
--- a/autoload/lsp/diag.vim
+++ b/autoload/lsp/diag.vim
@@ -251,7 +251,7 @@
 # process a diagnostic notification message from the LSP server
 # Notification: textDocument/publishDiagnostics
 # Param: PublishDiagnosticsParams
-export def DiagNotification(lspserver: dict<any>, uri: string, newDiags: list<dict<any>>): void
+export def DiagNotification(lspserver: dict<any>, uri: string, diags_arg: list<dict<any>>): void
   # Diagnostics are disabled for this server
   if lspserver.features->has_key('diagnostics') && !lspserver.features.diagnostics
     return
@@ -262,6 +262,11 @@   var bnr: number = fname->bufnr()
   if bnr == -1
     # Is this condition possible?
     return
+  endif
+
+  var newDiags: list<dict<any>> = diags_arg
+  if lspserver.processDiagHandler != null_function
+    newDiags = lspserver.processDiagHandler(diags_arg)
   endif
 
   # TODO: Is the buffer (bnr) always a loaded buffer? Should we load it here?
diff --git a/autoload/lsp/lsp.vim b/autoload/lsp/lsp.vim
index b2f6dd3e0bc4bbd57be11389573395d95f4ede18..edecb3ffba1ef3634aef4983e7951db4e3aa34e6 100644
--- a/autoload/lsp/lsp.vim
+++ b/autoload/lsp/lsp.vim
@@ -612,6 +612,11 @@     if server->has_key('customNotificationHandlers')
       customNotificationHandlers = server.customNotificationHandlers
     endif
 
+    var ProcessDiagHandler: func = null_function
+    if server->has_key('processDiagHandler')
+      ProcessDiagHandler = server.processDiagHandler
+    endif
+
     var features: dict<bool> = {}
     if server->has_key('features')
       features = server.features
@@ -661,6 +666,7 @@ 						    server.rootSearch,
 						    server.runIfSearch,
 						    server.runUnlessSearch,
 						    customNotificationHandlers,
+						    ProcessDiagHandler,
 						    features, server.debug)
 
     var ftypes = server.filetype
diff --git a/autoload/lsp/lspserver.vim b/autoload/lsp/lspserver.vim
index 89501a2c02498566cf1bff55d69e22a35f8c09a8..ccd3c4d2492443287e6a02ca43c92cc84580d20e 100644
--- a/autoload/lsp/lspserver.vim
+++ b/autoload/lsp/lspserver.vim
@@ -1505,6 +1505,7 @@ 			rootSearchFiles: list<any>,
 			runIfSearchFiles: list<any>,
 			runUnlessSearchFiles: list<any>,
 			customNotificationHandlers: dict<func>,
+			ProcessDiagHandler: func,
 			features: dict<bool>, debug_arg: bool): dict<any>
   var lspserver: dict<any> = {
     id: GetUniqueServerId(),
@@ -1514,6 +1515,7 @@     args: args,
     syncInit: isSync,
     initializationOptions: initializationOptions,
     customNotificationHandlers: customNotificationHandlers,
+    processDiagHandler: ProcessDiagHandler,
     features: features,
     running: false,
     ready: false,
diff --git a/doc/lsp.txt b/doc/lsp.txt
index 7ce342a0a60210b4d96c845355ef86b8681d0a7a..2cf47b728783a6246cde1d86da0c2845161a49f0 100644
--- a/doc/lsp.txt
+++ b/doc/lsp.txt
@@ -320,6 +320,13 @@ 						*lsp-cfg-omnicompl*
 	omnicompl	(Optional) a boolean value that enables (true)
 			or disables (false) omni-completion for this file
 			types. By default this is set to "v:true".
+						*lsp-cfg-processDiagHandler*
+	processDiagHandler
+			(Optional) A |Funcref| or |lambda| that takes a list of
+			language server diagnostics and returns a new list of
+			filtered, or otherwise changed diagnostics.  Can be used
+			to remove unwanted diagnostics, prefix the diagnostics
+			text, etc.
 						*lsp-cfg-syncInit*
 	syncInit        (Optional) for language servers (e.g. rust analyzer,
 			gopls, etc.) that take time to initialize and reply to