Index: clang-tools-extra/trunk/clangd/CodeComplete.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/CodeComplete.cpp
+++ clang-tools-extra/trunk/clangd/CodeComplete.cpp
@@ -1015,6 +1015,15 @@
     return std::move(Top).items();
   }
 
+  Optional<float> fuzzyScore(const CompletionCandidate &C) {
+    // Macros can be very spammy, so we only support prefix completion.
+    // We won't end up with underfull index results, as macros are sema-only.
+    if (C.SemaResult && C.SemaResult->Kind == CodeCompletionResult::RK_Macro &&
+        !C.Name.startswith_lower(Filter->pattern()))
+      return None;
+    return Filter->match(C.Name);
+  }
+
   // Scores a candidate and adds it to the TopN structure.
   void addCandidate(TopN<ScoredCandidate, ScoredCandidateGreater> &Candidates,
                     const CodeCompletionResult *SemaResult,
@@ -1027,7 +1036,7 @@
     SymbolQualitySignals Quality;
     SymbolRelevanceSignals Relevance;
     Relevance.Query = SymbolRelevanceSignals::CodeComplete;
-    if (auto FuzzyScore = Filter->match(C.Name))
+    if (auto FuzzyScore = fuzzyScore(C))
       Relevance.NameMatch = *FuzzyScore;
     else
       return;
Index: clang-tools-extra/trunk/unittests/clangd/CodeCompleteTests.cpp
===================================================================
--- clang-tools-extra/trunk/unittests/clangd/CodeCompleteTests.cpp
+++ clang-tools-extra/trunk/unittests/clangd/CodeCompleteTests.cpp
@@ -193,6 +193,7 @@
 
 TEST(CompletionTest, Filter) {
   std::string Body = R"cpp(
+    #define FooBarMacro
     int Abracadabra;
     int Alakazam;
     struct S {
@@ -202,7 +203,8 @@
     };
   )cpp";
   EXPECT_THAT(completions(Body + "int main() { S().Foba^ }").items,
-              AllOf(Has("FooBar"), Has("FooBaz"), Not(Has("Qux"))));
+              AllOf(Has("FooBar"), Has("FooBaz"), Not(Has("FooBarMacro")),
+                    Not(Has("Qux"))));
 
   EXPECT_THAT(completions(Body + "int main() { S().FR^ }").items,
               AllOf(Has("FooBar"), Not(Has("FooBaz")), Not(Has("Qux"))));