Index: clangd/index/dex/dexp/CMakeLists.txt
===================================================================
--- clangd/index/dex/dexp/CMakeLists.txt
+++ clangd/index/dex/dexp/CMakeLists.txt
@@ -1,3 +1,5 @@
+include_directories(${CMAKE_CURRENT_SOURCE_DIR}/..)
+include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../..)
 include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../../../)
 
 set(LLVM_LINK_COMPONENTS
Index: clangd/index/dex/dexp/Dexp.cpp
===================================================================
--- clangd/index/dex/dexp/Dexp.cpp
+++ clangd/index/dex/dexp/Dexp.cpp
@@ -12,13 +12,15 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "../../Serialization.h"
-#include "../Dex.h"
+#include "Dex.h"
+#include "Serialization.h"
+#include "SourceCode.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/LineEditor/LineEditor.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Error.h"
 #include "llvm/Support/Signals.h"
 
 using clang::clangd::FuzzyFindRequest;
@@ -52,6 +54,29 @@
   llvm::outs() << llvm::formatv("{0} took {1:ms+n}.\n", Name, Duration);
 }
 
+llvm::Expected<clang::clangd::SymbolID>
+getSymbolIDFromIndex(llvm::StringRef QualifiedName, const SymbolIndex *Index) {
+  FuzzyFindRequest Request;
+  Request.Scopes.emplace_back();
+  std::tie(Request.Scopes.back(), Request.Query) =
+      clang::clangd::splitQualifiedName(QualifiedName);
+  bool Found = false;
+  clang::clangd::SymbolID SymID;
+  // We choose the first one if there are overloaded symbols.
+  Index->fuzzyFind(Request, [&](const Symbol &Sym) {
+    std::string SymQualifiedName = (Sym.Scope + Sym.Name).str();
+    if (!Found && QualifiedName == SymQualifiedName) {
+      SymID = Sym.ID;
+      Found = true;
+    }
+  });
+  if (Found)
+    return SymID;
+
+  return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                 "Symbol not found in index.");
+}
+
 // REPL commands inherit from Command and contain their options as members.
 // Creating a Command populates parser options, parseAndRun() resets them.
 class Command {
@@ -88,7 +113,6 @@
 };
 
 // FIXME(kbobyrev): Ideas for more commands:
-// * find symbol references: print set of reference locations
 // * load/swap/reload index: this would make it possible to get rid of llvm::cl
 //   usages in the tool driver and actually use llvm::cl library in the REPL.
 // * show posting list density histogram (our dump data somewhere so that user
@@ -139,12 +163,21 @@
   cl::opt<std::string> ID{
       "id",
       cl::Positional,
-      cl::Required,
       cl::desc("Symbol ID to look up (hex)"),
   };
+  cl::opt<std::string> Name{
+      "name", cl::desc("Qualified name to look up."),
+  };
 
   void run() override {
-    auto SID = clang::clangd::SymbolID::fromStr(ID);
+    if (ID.getNumOccurrences() == 0 && Name.getNumOccurrences() == 0) {
+      llvm::outs()
+          << "Missing required argument: please provide -id or -name.\n";
+      return;
+    }
+    llvm::Expected<clang::clangd::SymbolID> SID =
+        ID.getNumOccurrences() ? clang::clangd::SymbolID::fromStr(ID)
+                               : getSymbolIDFromIndex(Name, Index);
     if (!SID) {
       llvm::outs() << llvm::toString(SID.takeError()) << "\n";
       return;
@@ -162,13 +195,59 @@
   }
 };
 
+class Refs : public Command {
+  cl::opt<std::string> ID{
+      "id", cl::Positional,
+      cl::desc("Symbol ID of the symbol being queried (hex)."),
+  };
+  cl::opt<std::string> Name{
+      "name", cl::desc("Qualified name of the symbol being queried."),
+  };
+  cl::opt<std::string> Filter{
+      "filter",
+      cl::init(".*"),
+      cl::desc(
+          "Print all results from files matching this regular expression."),
+  };
+
+  void run() override {
+    if (ID.getNumOccurrences() == 0 && Name.getNumOccurrences() == 0) {
+      llvm::outs()
+          << "Missing required argument: please provide -id or -name.\n";
+      return;
+    }
+    llvm::Expected<clang::clangd::SymbolID> SID =
+        ID.getNumOccurrences() ? clang::clangd::SymbolID::fromStr(ID)
+                               : getSymbolIDFromIndex(Name, Index);
+    if (!SID) {
+      llvm::outs() << llvm::toString(SID.takeError()) << "\n";
+      return;
+    }
+    clang::clangd::RefsRequest RefRequest;
+    RefRequest.IDs.insert(*SID);
+    llvm::Regex RegexFilter(Filter);
+    Index->refs(RefRequest, [&RegexFilter](const clang::clangd::Ref &R) {
+      auto U = clang::clangd::URI::parse(R.Location.FileURI);
+      if (!U) {
+        llvm::outs() << U.takeError();
+        return;
+      }
+      if (RegexFilter.match(U->body()))
+        llvm::outs() << R << "\n";
+    });
+  }
+};
+
 struct {
   const char *Name;
   const char *Description;
   std::function<std::unique_ptr<Command>()> Implementation;
 } CommandInfo[] = {
     {"find", "Search for symbols with fuzzyFind", llvm::make_unique<FuzzyFind>},
-    {"lookup", "Dump symbol details by ID", llvm::make_unique<Lookup>},
+    {"lookup", "Dump symbol details by ID or qualified name",
+     llvm::make_unique<Lookup>},
+    {"refs", "Find references by ID or qualified name",
+     llvm::make_unique<Refs>},
 };
 
 } // namespace