diff --git a/clang-tools-extra/clangd/ClangdServer.cpp b/clang-tools-extra/clangd/ClangdServer.cpp
--- a/clang-tools-extra/clangd/ClangdServer.cpp
+++ b/clang-tools-extra/clangd/ClangdServer.cpp
@@ -362,6 +362,7 @@
     ParseInput.Index = Index;
 
     CodeCompleteOpts.MainFileSignals = IP->Signals;
+    CodeCompleteOpts.AllScopes = Config::current().Completion.AllScopes;
     // FIXME(ibiryukov): even if Preamble is non-null, we may want to check
     // both the old and the new version in case only one of them matches.
     CodeCompleteResult Result = clangd::codeComplete(
diff --git a/clang-tools-extra/clangd/Config.h b/clang-tools-extra/clangd/Config.h
--- a/clang-tools-extra/clangd/Config.h
+++ b/clang-tools-extra/clangd/Config.h
@@ -106,6 +106,13 @@
     // ::). All nested namespaces are affected as well.
     std::vector<std::string> FullyQualifiedNamespaces;
   } Style;
+
+  /// Configures code completion feature.
+  struct {
+    /// Whether code completion includes results that are not visible in current
+    /// scopes.
+    bool AllScopes = true;
+  } Completion;
 };
 
 } // namespace clangd
diff --git a/clang-tools-extra/clangd/ConfigCompile.cpp b/clang-tools-extra/clangd/ConfigCompile.cpp
--- a/clang-tools-extra/clangd/ConfigCompile.cpp
+++ b/clang-tools-extra/clangd/ConfigCompile.cpp
@@ -192,6 +192,7 @@
     compile(std::move(F.CompileFlags));
     compile(std::move(F.Index));
     compile(std::move(F.Diagnostics));
+    compile(std::move(F.Completion));
   }
 
   void compile(Fragment::IfBlock &&F) {
@@ -463,6 +464,15 @@
     }
   }
 
+  void compile(Fragment::CompletionBlock &&F) {
+    if (F.AllScopes) {
+      Out.Apply.push_back(
+          [AllScopes(**F.AllScopes)](const Params &, Config &C) {
+            C.Completion.AllScopes = AllScopes;
+          });
+    }
+  }
+
   constexpr static llvm::SourceMgr::DiagKind Error = llvm::SourceMgr::DK_Error;
   constexpr static llvm::SourceMgr::DiagKind Warning =
       llvm::SourceMgr::DK_Warning;
diff --git a/clang-tools-extra/clangd/ConfigFragment.h b/clang-tools-extra/clangd/ConfigFragment.h
--- a/clang-tools-extra/clangd/ConfigFragment.h
+++ b/clang-tools-extra/clangd/ConfigFragment.h
@@ -238,6 +238,14 @@
     std::vector<Located<std::string>> FullyQualifiedNamespaces;
   };
   StyleBlock Style;
+
+  /// Describes code completion preferences.
+  struct CompletionBlock {
+    /// Whether code completion should include suggestions from scopes that are
+    /// not visible. The required scope prefix will be inserted.
+    llvm::Optional<Located<bool>> AllScopes;
+  };
+  CompletionBlock Completion;
 };
 
 } // namespace config
diff --git a/clang-tools-extra/clangd/ConfigYAML.cpp b/clang-tools-extra/clangd/ConfigYAML.cpp
--- a/clang-tools-extra/clangd/ConfigYAML.cpp
+++ b/clang-tools-extra/clangd/ConfigYAML.cpp
@@ -63,6 +63,7 @@
     Dict.handle("Index", [&](Node &N) { parse(F.Index, N); });
     Dict.handle("Style", [&](Node &N) { parse(F.Style, N); });
     Dict.handle("Diagnostics", [&](Node &N) { parse(F.Diagnostics, N); });
+    Dict.handle("Completion", [&](Node &N) { parse(F.Completion, N); });
     Dict.parse(N);
     return !(N.failed() || HadError);
   }
@@ -165,6 +166,19 @@
     Dict.parse(N);
   }
 
+  void parse(Fragment::CompletionBlock &F, Node &N) {
+    DictParser Dict("Completion", this);
+    Dict.handle("AllScopes", [&](Node &N) {
+      if (auto Value = scalarValue(N, "AllScopes")) {
+        if (auto AllScopes = llvm::yaml::parseBool(**Value))
+          F.AllScopes = *AllScopes;
+        else
+          warning("AllScopes should be a boolean", N);
+      }
+    });
+    Dict.parse(N);
+  }
+
   // Helper for parsing mapping nodes (dictionaries).
   // We don't use YamlIO as we want to control over unknown keys.
   class DictParser {
diff --git a/clang-tools-extra/clangd/tool/ClangdMain.cpp b/clang-tools-extra/clangd/tool/ClangdMain.cpp
--- a/clang-tools-extra/clangd/tool/ClangdMain.cpp
+++ b/clang-tools-extra/clangd/tool/ClangdMain.cpp
@@ -623,6 +623,7 @@
     if (!EnableBackgroundIndex) {
       BGPolicy = Config::BackgroundPolicy::Skip;
     }
+
     Frag = [=](const config::Params &, Config &C) {
       if (CDBSearch)
         C.CompileFlags.CDBSearch = *CDBSearch;
@@ -630,6 +631,8 @@
         C.Index.External = *IndexSpec;
       if (BGPolicy)
         C.Index.Background = *BGPolicy;
+      if (AllScopesCompletion.getNumOccurrences())
+        C.Completion.AllScopes = AllScopesCompletion;
       return true;
     };
   }
@@ -827,7 +830,6 @@
     Opts.CodeComplete.IncludeIndicator.NoInsert.clear();
   }
   Opts.CodeComplete.EnableFunctionArgSnippets = EnableFunctionArgSnippets;
-  Opts.CodeComplete.AllScopes = AllScopesCompletion;
   Opts.CodeComplete.RunParser = CodeCompletionParse;
   Opts.CodeComplete.RankingModel = RankingModel;
 
diff --git a/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp b/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp
--- a/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ConfigCompileTests.cpp
@@ -443,6 +443,22 @@
   ASSERT_FALSE(Conf.Index.External);
 #endif
 }
+
+TEST_F(ConfigCompileTests, AllScopes) {
+  // Defaults to true.
+  EXPECT_TRUE(compileAndApply());
+  EXPECT_TRUE(Conf.Completion.AllScopes);
+
+  Frag = {};
+  Frag.Completion.AllScopes = false;
+  EXPECT_TRUE(compileAndApply());
+  EXPECT_FALSE(Conf.Completion.AllScopes);
+
+  Frag = {};
+  Frag.Completion.AllScopes = true;
+  EXPECT_TRUE(compileAndApply());
+  EXPECT_TRUE(Conf.Completion.AllScopes);
+}
 } // namespace
 } // namespace config
 } // namespace clangd
diff --git a/clang-tools-extra/clangd/unittests/ConfigYAMLTests.cpp b/clang-tools-extra/clangd/unittests/ConfigYAMLTests.cpp
--- a/clang-tools-extra/clangd/unittests/ConfigYAMLTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ConfigYAMLTests.cpp
@@ -10,10 +10,12 @@
 #include "ConfigFragment.h"
 #include "ConfigTesting.h"
 #include "Protocol.h"
+#include "llvm/ADT/None.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/SMLoc.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Support/SourceMgr.h"
+#include "llvm/Testing/Support/SupportHelpers.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 
@@ -164,6 +166,35 @@
   EXPECT_THAT(*Results[0].Index.External.getValue()->Server, Val("bar"));
 }
 
+TEST(ParseYAML, AllScopes) {
+  CapturedDiags Diags;
+  Annotations YAML(R"yaml(
+Completion:
+  AllScopes: True
+  )yaml");
+  auto Results =
+      Fragment::parseYAML(YAML.code(), "config.yaml", Diags.callback());
+  ASSERT_THAT(Diags.Diagnostics, IsEmpty());
+  ASSERT_EQ(Results.size(), 1u);
+  EXPECT_THAT(Results[0].Completion.AllScopes, llvm::ValueIs(Val(true)));
+}
+
+TEST(ParseYAML, AllScopesWarn) {
+  CapturedDiags Diags;
+  Annotations YAML(R"yaml(
+Completion:
+  AllScopes: $diagrange[[Truex]]
+  )yaml");
+  auto Results =
+      Fragment::parseYAML(YAML.code(), "config.yaml", Diags.callback());
+  EXPECT_THAT(Diags.Diagnostics,
+              ElementsAre(AllOf(DiagMessage("AllScopes should be a boolean"),
+                                DiagKind(llvm::SourceMgr::DK_Warning),
+                                DiagPos(YAML.range("diagrange").start),
+                                DiagRange(YAML.range("diagrange")))));
+  ASSERT_EQ(Results.size(), 1u);
+  EXPECT_THAT(Results[0].Completion.AllScopes, testing::Eq(llvm::None));
+}
 } // namespace
 } // namespace config
 } // namespace clangd