Index: clangd/AST.h
===================================================================
--- clangd/AST.h
+++ clangd/AST.h
@@ -26,7 +26,10 @@
 ///
 /// The returned location is usually the spelling location where the name of the
 /// decl occurs in the code.
-SourceLocation findNameLoc(const clang::Decl* D);
+SourceLocation findNameLoc(const Decl *D);
+
+/// Returns true iff all redecls of \p D are in the main file.
+bool allDeclsInMainFile(const Decl *D);
 
 } // namespace clangd
 } // namespace clang
Index: clangd/AST.cpp
===================================================================
--- clangd/AST.cpp
+++ clangd/AST.cpp
@@ -17,8 +17,8 @@
 namespace clangd {
 using namespace llvm;
 
-SourceLocation findNameLoc(const clang::Decl* D) {
-  const auto& SM = D->getASTContext().getSourceManager();
+SourceLocation findNameLoc(const Decl *D) {
+  const auto &SM = D->getASTContext().getSourceManager();
   // FIXME: Revisit the strategy, the heuristic is limitted when handling
   // macros, we should use the location where the whole definition occurs.
   SourceLocation SpellingLoc = SM.getSpellingLoc(D->getLocation());
@@ -38,5 +38,15 @@
   return SpellingLoc;
 }
 
+bool allDeclsInMainFile(const Decl *D) {
+  const SourceManager &SM = D->getASTContext().getSourceManager();
+  for (auto *Redecl : D->redecls()) {
+    auto Loc = Redecl->getLocation();
+    if (!SM.isWrittenInMainFile(Loc))
+      return false;
+  }
+  return true;
+}
+
 } // namespace clangd
 } // namespace clang
Index: clangd/Quality.h
===================================================================
--- clangd/Quality.h
+++ clangd/Quality.h
@@ -47,6 +47,7 @@
   unsigned SemaCCPriority = 0; // 1-80, 1 is best. 0 means absent.
                                // FIXME: this is actually a mix of symbol
                                //        quality and relevance. Untangle this.
+  bool AllDeclsInMainFile = false;
   bool Deprecated = false;
   unsigned References = 0;
 
Index: clangd/Quality.cpp
===================================================================
--- clangd/Quality.cpp
+++ clangd/Quality.cpp
@@ -7,6 +7,7 @@
 //
 //===---------------------------------------------------------------------===//
 #include "Quality.h"
+#include "AST.h"
 #include "index/Index.h"
 #include "clang/Sema/CodeCompleteConsumer.h"
 #include "llvm/Support/FormatVariadic.h"
@@ -19,7 +20,8 @@
 
 void SymbolQualitySignals::merge(const CodeCompletionResult &SemaCCResult) {
   SemaCCPriority = SemaCCResult.Priority;
-
+  if (SemaCCResult.Declaration)
+    AllDeclsInMainFile = allDeclsInMainFile(SemaCCResult.Declaration);
   if (SemaCCResult.Availability == CXAvailability_Deprecated)
     Deprecated = true;
 }
@@ -41,6 +43,10 @@
     // Priority 80 is a really bad score.
     Score *= 2 - std::min<float>(80, SemaCCPriority) / 40;
 
+  // Things declared in the main file get a large boost.
+  if (AllDeclsInMainFile)
+    Score *= 2;
+
   if (Deprecated)
     Score *= 0.1;
 
Index: unittests/clangd/QualityTests.cpp
===================================================================
--- unittests/clangd/QualityTests.cpp
+++ unittests/clangd/QualityTests.cpp
@@ -118,6 +118,45 @@
   EXPECT_LT(sortText(0, "a"), sortText(0, "z"));
 }
 
+TEST(QualityTests, BoostCurrentFileDecls) {
+  TestTU Test;
+  Test.HeaderFilename = "foo.h";
+  Test.HeaderCode = R"cpp(
+    int test_func_in_header();
+    int test_func_in_header_and_cpp();
+    )cpp";
+  Test.Code = R"cpp(
+    #include "foo.h"
+    int ::test_func_in_header_and_cpp() {
+    }
+    int test_func_in_cpp();
+
+    int test() {
+      test_func_^
+    }
+  )cpp";
+
+  ParsedAST AST = Test.build();
+
+  SymbolQualitySignals FuncInCpp;
+  FuncInCpp.merge(CodeCompletionResult(&findDecl(AST, "test_func_in_cpp"),
+                                       CCP_Declaration));
+  EXPECT_TRUE(FuncInCpp.AllDeclsInMainFile);
+
+  SymbolQualitySignals FuncInHeader;
+  FuncInHeader.merge(CodeCompletionResult(&findDecl(AST, "test_func_in_header"),
+                                          CCP_Declaration));
+  EXPECT_FALSE(FuncInHeader.AllDeclsInMainFile);
+
+  SymbolQualitySignals FuncInHeaderAndCpp;
+  FuncInHeaderAndCpp.merge(CodeCompletionResult(
+      &findDecl(AST, "test_func_in_header_and_cpp"), CCP_Declaration));
+  EXPECT_FALSE(FuncInHeaderAndCpp.AllDeclsInMainFile);
+
+  EXPECT_LE(FuncInHeader.evaluate(), FuncInCpp.evaluate());
+  EXPECT_FLOAT_EQ(FuncInHeader.evaluate(), FuncInHeaderAndCpp.evaluate());
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang
Index: unittests/clangd/TestTU.cpp
===================================================================
--- unittests/clangd/TestTU.cpp
+++ unittests/clangd/TestTU.cpp
@@ -1,5 +1,4 @@
-//===--- TestTU.cpp - Scratch source files for testing ------------*-
-//C++-*-===//
+//===--- TestTU.cpp - Scratch source files for testing -------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -78,11 +77,11 @@
     auto *ND = dyn_cast<NamedDecl>(D);
     if (!ND || ND->getNameAsString() != QName)
       continue;
-    if (Result) {
+    if (Result && ND->getCanonicalDecl() != Result) {
       ADD_FAILURE() << "Multiple Decls named " << QName;
       assert(false && "QName is not unique");
     }
-    Result = ND;
+    Result = cast<NamedDecl>(ND->getCanonicalDecl());
   }
   if (!Result) {
     ADD_FAILURE() << "No Decl named " << QName << " in AST";