Index: clang-tools-extra/trunk/clangd/AST.h
===================================================================
--- clang-tools-extra/trunk/clangd/AST.h
+++ clang-tools-extra/trunk/clangd/AST.h
@@ -16,6 +16,7 @@
 
 #include "clang/AST/Decl.h"
 #include "clang/Basic/SourceLocation.h"
+#include "index/Index.h"
 
 namespace clang {
 class SourceManager;
@@ -33,6 +34,9 @@
 /// like inline namespaces.
 std::string printQualifiedName(const NamedDecl &ND);
 
+/// Gets the symbol ID for a declaration, if possible.
+llvm::Optional<SymbolID> getSymbolID(const Decl *D);
+
 } // namespace clangd
 } // namespace clang
 
Index: clang-tools-extra/trunk/clangd/AST.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/AST.cpp
+++ clang-tools-extra/trunk/clangd/AST.cpp
@@ -12,6 +12,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Decl.h"
 #include "clang/Basic/SourceManager.h"
+#include "clang/Index/USRGeneration.h"
 
 namespace clang {
 namespace clangd {
@@ -53,5 +54,12 @@
   return QName;
 }
 
+llvm::Optional<SymbolID> getSymbolID(const Decl *D) {
+  llvm::SmallString<128> USR;
+  if (index::generateUSRForDecl(D, USR))
+    return None;
+  return SymbolID(USR);
+}
+
 } // namespace clangd
 } // namespace clang
Index: clang-tools-extra/trunk/clangd/CodeComplete.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/CodeComplete.cpp
+++ clang-tools-extra/trunk/clangd/CodeComplete.cpp
@@ -396,10 +396,7 @@
   switch (R.Kind) {
   case CodeCompletionResult::RK_Declaration:
   case CodeCompletionResult::RK_Pattern: {
-    llvm::SmallString<128> USR;
-    if (/*Ignore=*/clang::index::generateUSRForDecl(R.Declaration, USR))
-      return None;
-    return SymbolID(USR);
+    return clang::clangd::getSymbolID(R.Declaration);
   }
   case CodeCompletionResult::RK_Macro:
     // FIXME: Macros do have USRs, but the CCR doesn't contain enough info.
Index: clang-tools-extra/trunk/clangd/XRefs.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/XRefs.cpp
+++ clang-tools-extra/trunk/clangd/XRefs.cpp
@@ -202,15 +202,6 @@
   return L;
 }
 
-// Get the symbol ID for a declaration, if possible.
-llvm::Optional<SymbolID> getSymbolID(const Decl *D) {
-  llvm::SmallString<128> USR;
-  if (index::generateUSRForDecl(D, USR)) {
-    return None;
-  }
-  return SymbolID(USR);
-}
-
 } // namespace
 
 std::vector<Location> findDefinitions(ParsedAST &AST, Position Pos,
Index: clang-tools-extra/trunk/clangd/index/SymbolCollector.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/index/SymbolCollector.cpp
+++ clang-tools-extra/trunk/clangd/index/SymbolCollector.cpp
@@ -320,21 +320,20 @@
   if (!shouldCollectSymbol(*ND, *ASTCtx, Opts))
     return true;
 
-  llvm::SmallString<128> USR;
-  if (index::generateUSRForDecl(ND, USR))
+  auto ID = getSymbolID(ND);
+  if (!ID)
     return true;
-  SymbolID ID(USR);
 
   const NamedDecl &OriginalDecl = *cast<NamedDecl>(ASTNode.OrigD);
-  const Symbol *BasicSymbol = Symbols.find(ID);
+  const Symbol *BasicSymbol = Symbols.find(*ID);
   if (!BasicSymbol) // Regardless of role, ND is the canonical declaration.
-    BasicSymbol = addDeclaration(*ND, std::move(ID));
+    BasicSymbol = addDeclaration(*ND, std::move(*ID));
   else if (isPreferredDeclaration(OriginalDecl, Roles))
     // If OriginalDecl is preferred, replace the existing canonical
     // declaration (e.g. a class forward declaration). There should be at most
     // one duplicate as we expect to see only one preferred declaration per
     // TU, because in practice they are definitions.
-    BasicSymbol = addDeclaration(OriginalDecl, std::move(ID));
+    BasicSymbol = addDeclaration(OriginalDecl, std::move(*ID));
 
   if (Roles & static_cast<unsigned>(index::SymbolRole::Definition))
     addDefinition(OriginalDecl, *BasicSymbol);
@@ -423,9 +422,9 @@
     }
   };
   for (const NamedDecl *ND : ReferencedDecls) {
-    llvm::SmallString<128> USR;
-    if (!index::generateUSRForDecl(ND, USR))
-      IncRef(SymbolID(USR));
+    if (auto ID = getSymbolID(ND)) {
+      IncRef(*ID);
+    }
   }
   if (Opts.CollectMacro) {
     assert(PP);