Index: clangd/Diagnostics.cpp
===================================================================
--- clangd/Diagnostics.cpp
+++ clangd/Diagnostics.cpp
@@ -161,10 +161,12 @@
 ///
 ///     dir1/dir2/dir3/../../dir4/header.h:12:23
 ///     note: candidate function not viable: requires 3 arguments
-std::string mainMessage(const Diag &D) {
+std::string mainMessage(const Diag &D, bool FixAvailable) {
   std::string Result;
   llvm::raw_string_ostream OS(Result);
   OS << D.Message;
+  if (FixAvailable)
+    OS << " (fix available)";
   for (auto &Note : D.Notes) {
     OS << "\n\n";
     printDiag(OS, Note);
@@ -250,7 +252,7 @@
 
   {
     clangd::Diagnostic Main = FillBasicFields(D);
-    Main.message = mainMessage(D);
+    Main.message = mainMessage(D, /*FixAvailable=*/!D.Fixes.empty());
     if (Opts.EmbedFixesInDiagnostics) {
       Main.codeActions.emplace();
       for (const auto &Fix : D.Fixes)
Index: test/clangd/diagnostic-category.test
===================================================================
--- test/clangd/diagnostic-category.test
+++ test/clangd/diagnostic-category.test
@@ -7,7 +7,7 @@
 # CHECK-NEXT:     "diagnostics": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "category": "Semantic Issue",
-# CHECK-NEXT:        "message": "Use of 'Point' with tag type that does not match previous declaration\n\nfoo.c:1:8: note: previous use is here",
+# CHECK-NEXT:        "message": "Use of 'Point' with tag type that does not match previous declaration (fix available)\n\nfoo.c:1:8: note: previous use is here",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {
 # CHECK-NEXT:            "character": 22,
Index: test/clangd/diagnostics.test
===================================================================
--- test/clangd/diagnostics.test
+++ test/clangd/diagnostics.test
@@ -6,7 +6,7 @@
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
-# CHECK-NEXT:        "message": "Return type of 'main' is not 'int'",
+# CHECK-NEXT:        "message": "Return type of 'main' is not 'int' (fix available)",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {
 # CHECK-NEXT:            "character": 4,
Index: test/clangd/did-change-configuration-params.test
===================================================================
--- test/clangd/did-change-configuration-params.test
+++ test/clangd/did-change-configuration-params.test
@@ -24,7 +24,7 @@
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
-# CHECK-NEXT:        "message": "Variable 'i' is uninitialized when used here",
+# CHECK-NEXT:        "message": "Variable 'i' is uninitialized when used here (fix available)",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {
 # CHECK-NEXT:            "character": 28,
Index: test/clangd/execute-command.test
===================================================================
--- test/clangd/execute-command.test
+++ test/clangd/execute-command.test
@@ -6,7 +6,7 @@
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
-# CHECK-NEXT:        "message": "Using the result of an assignment as a condition without parentheses",
+# CHECK-NEXT:        "message": "Using the result of an assignment as a condition without parentheses (fix available)",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {
 # CHECK-NEXT:            "character": 37,
Index: test/clangd/fixits-codeaction.test
===================================================================
--- test/clangd/fixits-codeaction.test
+++ test/clangd/fixits-codeaction.test
@@ -6,7 +6,7 @@
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
-# CHECK-NEXT:        "message": "Using the result of an assignment as a condition without parentheses",
+# CHECK-NEXT:        "message": "Using the result of an assignment as a condition without parentheses (fix available)",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {
 # CHECK-NEXT:            "character": 37,
@@ -23,14 +23,14 @@
 # CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
 # CHECK-NEXT:  }
 ---
-{"jsonrpc":"2.0","id":2,"method":"textDocument/codeAction","params":{"textDocument":{"uri":"test:///foo.c"},"range":{"start":{"line":104,"character":13},"end":{"line":0,"character":35}},"context":{"diagnostics":[{"range":{"start": {"line": 0, "character": 32}, "end": {"line": 0, "character": 37}},"severity":2,"message":"Using the result of an assignment as a condition without parentheses"}]}}}
+{"jsonrpc":"2.0","id":2,"method":"textDocument/codeAction","params":{"textDocument":{"uri":"test:///foo.c"},"range":{"start":{"line":104,"character":13},"end":{"line":0,"character":35}},"context":{"diagnostics":[{"range":{"start": {"line": 0, "character": 32}, "end": {"line": 0, "character": 37}},"severity":2,"message":"Using the result of an assignment as a condition without parentheses (fix available)"}]}}}
 #      CHECK:  "id": 2,
 # CHECK-NEXT:  "jsonrpc": "2.0",
 # CHECK-NEXT:  "result": [
 # CHECK-NEXT:    {
 # CHECK-NEXT:      "diagnostics": [
 # CHECK-NEXT:        {
-# CHECK-NEXT:          "message": "Using the result of an assignment as a condition without parentheses",
+# CHECK-NEXT:          "message": "Using the result of an assignment as a condition without parentheses (fix available)",
 # CHECK-NEXT:          "range": {
 # CHECK-NEXT:            "end": {
 # CHECK-NEXT:              "character": 37,
@@ -82,7 +82,7 @@
 # CHECK-NEXT:    {
 # CHECK-NEXT:      "diagnostics": [
 # CHECK-NEXT:        {
-# CHECK-NEXT:          "message": "Using the result of an assignment as a condition without parentheses",
+# CHECK-NEXT:          "message": "Using the result of an assignment as a condition without parentheses (fix available)",
 # CHECK-NEXT:          "range": {
 # CHECK-NEXT:            "end": {
 # CHECK-NEXT:              "character": 37,
Index: test/clangd/fixits-command.test
===================================================================
--- test/clangd/fixits-command.test
+++ test/clangd/fixits-command.test
@@ -6,7 +6,7 @@
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
-# CHECK-NEXT:        "message": "Using the result of an assignment as a condition without parentheses",
+# CHECK-NEXT:        "message": "Using the result of an assignment as a condition without parentheses (fix available)",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {
 # CHECK-NEXT:            "character": 37,
@@ -23,7 +23,7 @@
 # CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
 # CHECK-NEXT:  }
 ---
-{"jsonrpc":"2.0","id":2,"method":"textDocument/codeAction","params":{"textDocument":{"uri":"test:///foo.c"},"range":{"start":{"line":0,"character":13},"end":{"line":0,"character":35}},"context":{"diagnostics":[{"range":{"start": {"line": 0, "character": 32}, "end": {"line": 0, "character": 37}},"severity":2,"message":"Using the result of an assignment as a condition without parentheses"}]}}}
+{"jsonrpc":"2.0","id":2,"method":"textDocument/codeAction","params":{"textDocument":{"uri":"test:///foo.c"},"range":{"start":{"line":0,"character":13},"end":{"line":0,"character":35}},"context":{"diagnostics":[{"range":{"start": {"line": 0, "character": 32}, "end": {"line": 0, "character": 37}},"severity":2,"message":"Using the result of an assignment as a condition without parentheses (fix available)"}]}}}
 #      CHECK:  "id": 2,
 # CHECK-NEXT:  "jsonrpc": "2.0",
 # CHECK-NEXT:  "result": [
@@ -92,7 +92,7 @@
 # CHECK-NEXT:    }
 # CHECK-NEXT:  ]
 ---
-{"jsonrpc":"2.0","id":3,"method":"textDocument/codeAction","params":{"textDocument":{"uri":"test:///foo.c"},"range":{"start":{"line":0,"character":13},"end":{"line":0,"character":35}},"context":{"diagnostics":[{"range":{"start": {"line": 0, "character": 32}, "end": {"line": 0, "character": 37}},"severity":2,"message":"Using the result of an assignment as a condition without parentheses"}]}}}
+{"jsonrpc":"2.0","id":3,"method":"textDocument/codeAction","params":{"textDocument":{"uri":"test:///foo.c"},"range":{"start":{"line":0,"character":13},"end":{"line":0,"character":35}},"context":{"diagnostics":[{"range":{"start": {"line": 0, "character": 32}, "end": {"line": 0, "character": 37}},"severity":2,"message":"Using the result of an assignment as a condition without parentheses (fix available)"}]}}}
 # Make sure unused "code" and "source" fields ignored gracefully
 #      CHECK:  "id": 3,
 # CHECK-NEXT:  "jsonrpc": "2.0",
Index: test/clangd/fixits-embed-in-diagnostic.test
===================================================================
--- test/clangd/fixits-embed-in-diagnostic.test
+++ test/clangd/fixits-embed-in-diagnostic.test
@@ -31,7 +31,7 @@
 # CHECK-NEXT:            "title": "change 'union' to 'struct'"
 # CHECK-NEXT:          }
 # CHECK-NEXT:        ],
-# CHECK-NEXT:        "message": "Use of 'Point' with tag type that does not match previous declaration\n\nfoo.c:1:8: note: previous use is here",
+# CHECK-NEXT:        "message": "Use of 'Point' with tag type that does not match previous declaration (fix available)\n\nfoo.c:1:8: note: previous use is here",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {
 # CHECK-NEXT:            "character": 22,
Index: unittests/clangd/DiagnosticsTests.cpp
===================================================================
--- unittests/clangd/DiagnosticsTests.cpp
+++ unittests/clangd/DiagnosticsTests.cpp
@@ -246,7 +246,8 @@
   };
 
   // Diagnostics should turn into these:
-  clangd::Diagnostic MainLSP = MatchingLSP(D, R"(Something terrible happened
+  clangd::Diagnostic MainLSP =
+      MatchingLSP(D, R"(Something terrible happened (fix available)
 
 main.cpp:6:7: remark: declared somewhere in the main file