Index: clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.h
===================================================================
--- clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.h
+++ clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.h
@@ -29,6 +29,7 @@
 } // namespace tooling
 
 namespace tidy {
+class CachedGlobList;
 
 /// A detected error complete with information to display diagnostic and
 /// automatic fix.
@@ -196,7 +197,7 @@
 
   std::string CurrentFile;
   ClangTidyOptions CurrentOptions;
-  class CachedGlobList;
+
   std::unique_ptr<CachedGlobList> CheckFilter;
   std::unique_ptr<CachedGlobList> WarningAsErrorFilter;
 
Index: clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp
===================================================================
--- clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp
+++ clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp
@@ -149,29 +149,6 @@
     : tooling::Diagnostic(CheckName, DiagLevel, BuildDirectory),
       IsWarningAsError(IsWarningAsError) {}
 
-class ClangTidyContext::CachedGlobList {
-public:
-  CachedGlobList(StringRef Globs) : Globs(Globs) {}
-
-  bool contains(StringRef S) {
-    switch (auto &Result = Cache[S]) {
-    case Yes:
-      return true;
-    case No:
-      return false;
-    case None:
-      Result = Globs.contains(S) ? Yes : No;
-      return Result == Yes;
-    }
-    llvm_unreachable("invalid enum");
-  }
-
-private:
-  GlobList Globs;
-  enum Tristate { None, Yes, No };
-  llvm::StringMap<Tristate> Cache;
-};
-
 ClangTidyContext::ClangTidyContext(
     std::unique_ptr<ClangTidyOptionsProvider> OptionsProvider,
     bool AllowEnablingAnalyzerAlphaCheckers)
Index: clang-tools-extra/clang-tidy/GlobList.h
===================================================================
--- clang-tools-extra/clang-tidy/GlobList.h
+++ clang-tools-extra/clang-tidy/GlobList.h
@@ -11,6 +11,7 @@
 
 #include "clang/Basic/LLVM.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Regex.h"
 
@@ -39,7 +40,6 @@
   bool contains(StringRef S) const;
 
 private:
-
   struct GlobListItem {
     bool IsPositive;
     llvm::Regex Regex;
@@ -47,6 +47,22 @@
   SmallVector<GlobListItem, 0> Items;
 };
 
+/// A \p GlobList that caches search results, so that search is performed only
+/// once for the same query.
+class CachedGlobList {
+public:
+  /// \see GlobList::GlobList
+  CachedGlobList(StringRef Globs, bool KeepNegativeGlobs = true);
+
+  /// \see GlobList::contains
+  bool contains(StringRef S);
+
+private:
+  GlobList Globs;
+  enum Tristate { None, Yes, No };
+  llvm::StringMap<Tristate> Cache;
+};
+
 } // end namespace tidy
 } // end namespace clang
 
Index: clang-tools-extra/clang-tidy/GlobList.cpp
===================================================================
--- clang-tools-extra/clang-tidy/GlobList.cpp
+++ clang-tools-extra/clang-tidy/GlobList.cpp
@@ -62,3 +62,19 @@
   }
   return false;
 }
+
+CachedGlobList::CachedGlobList(StringRef Globs, bool KeepNegativeGlobs)
+    : Globs(Globs, KeepNegativeGlobs) {}
+
+bool CachedGlobList::contains(StringRef S) {
+  switch (auto &Result = Cache[S]) {
+  case Yes:
+    return true;
+  case No:
+    return false;
+  case None:
+    Result = Globs.contains(S) ? Yes : No;
+    return Result == Yes;
+  }
+  llvm_unreachable("invalid enum");
+}
Index: clang-tools-extra/unittests/clang-tidy/GlobListTest.cpp
===================================================================
--- clang-tools-extra/unittests/clang-tidy/GlobListTest.cpp
+++ clang-tools-extra/unittests/clang-tidy/GlobListTest.cpp
@@ -4,15 +4,20 @@
 namespace clang {
 namespace tidy {
 
-TEST(GlobList, Empty) {
-  GlobList Filter("");
+template <typename GlobListT> struct GlobListTest : public ::testing::Test {};
+
+using GlobListTypes = ::testing::Types<GlobList, CachedGlobList>;
+TYPED_TEST_SUITE(GlobListTest, GlobListTypes);
+
+TYPED_TEST(GlobListTest, Empty) {
+  TypeParam Filter("");
 
   EXPECT_TRUE(Filter.contains(""));
   EXPECT_FALSE(Filter.contains("aaa"));
 }
 
-TEST(GlobList, Nothing) {
-  GlobList Filter("-*");
+TYPED_TEST(GlobListTest, Nothing) {
+  TypeParam Filter("-*");
 
   EXPECT_FALSE(Filter.contains(""));
   EXPECT_FALSE(Filter.contains("a"));
@@ -21,8 +26,8 @@
   EXPECT_FALSE(Filter.contains("*"));
 }
 
-TEST(GlobList, Everything) {
-  GlobList Filter("*");
+TYPED_TEST(GlobListTest, Everything) {
+  TypeParam Filter("*");
 
   EXPECT_TRUE(Filter.contains(""));
   EXPECT_TRUE(Filter.contains("aaaa"));
@@ -31,8 +36,8 @@
   EXPECT_TRUE(Filter.contains("*"));
 }
 
-TEST(GlobList, OneSimplePattern) {
-  GlobList Filter("aaa");
+TYPED_TEST(GlobListTest, OneSimplePattern) {
+  TypeParam Filter("aaa");
 
   EXPECT_TRUE(Filter.contains("aaa"));
   EXPECT_FALSE(Filter.contains(""));
@@ -41,8 +46,8 @@
   EXPECT_FALSE(Filter.contains("bbb"));
 }
 
-TEST(GlobList, TwoSimplePatterns) {
-  GlobList Filter("aaa,bbb");
+TYPED_TEST(GlobListTest, TwoSimplePatterns) {
+  TypeParam Filter("aaa,bbb");
 
   EXPECT_TRUE(Filter.contains("aaa"));
   EXPECT_TRUE(Filter.contains("bbb"));
@@ -52,11 +57,11 @@
   EXPECT_FALSE(Filter.contains("bbbb"));
 }
 
-TEST(GlobList, PatternPriority) {
+TYPED_TEST(GlobListTest, PatternPriority) {
   // The last glob that matches the string decides whether that string is
   // included or excluded.
   {
-    GlobList Filter("a*,-aaa");
+    TypeParam Filter("a*,-aaa");
 
     EXPECT_FALSE(Filter.contains(""));
     EXPECT_TRUE(Filter.contains("a"));
@@ -65,7 +70,7 @@
     EXPECT_TRUE(Filter.contains("aaaa"));
   }
   {
-    GlobList Filter("-aaa,a*");
+    TypeParam Filter("-aaa,a*");
 
     EXPECT_FALSE(Filter.contains(""));
     EXPECT_TRUE(Filter.contains("a"));
@@ -75,15 +80,16 @@
   }
 }
 
-TEST(GlobList, WhitespacesAtBegin) {
-  GlobList Filter("-*,   a.b.*");
+TYPED_TEST(GlobListTest, WhitespacesAtBegin) {
+  TypeParam Filter("-*,   a.b.*");
 
   EXPECT_TRUE(Filter.contains("a.b.c"));
   EXPECT_FALSE(Filter.contains("b.c"));
 }
 
-TEST(GlobList, Complex) {
-  GlobList Filter("*,-a.*, -b.*, \r  \n  a.1.* ,-a.1.A.*,-..,-...,-..+,-*$, -*qwe* ");
+TYPED_TEST(GlobListTest, Complex) {
+  TypeParam Filter(
+      "*,-a.*, -b.*, \r  \n  a.1.* ,-a.1.A.*,-..,-...,-..+,-*$, -*qwe* ");
 
   EXPECT_TRUE(Filter.contains("aaa"));
   EXPECT_TRUE(Filter.contains("qqq"));