diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -1513,19 +1513,21 @@
 //     Extra additions to <utility>
 //===----------------------------------------------------------------------===//
 
-/// Function object to check whether the first component of a std::pair
-/// compares less than the first component of another std::pair.
+/// Function object to check whether the first component of a container
+/// supported by std::get (like std::pair and std::tuple) compares less than the
+/// first component of another container.
 struct less_first {
   template <typename T> bool operator()(const T &lhs, const T &rhs) const {
-    return std::less<>()(lhs.first, rhs.first);
+    return std::less<>()(std::get<0>(lhs), std::get<0>(rhs));
   }
 };
 
-/// Function object to check whether the second component of a std::pair
-/// compares less than the second component of another std::pair.
+/// Function object to check whether the second component of a container
+/// supported by std::get (like std::pair and std::tuple) compares less than the
+/// second component of another container.
 struct less_second {
   template <typename T> bool operator()(const T &lhs, const T &rhs) const {
-    return std::less<>()(lhs.second, rhs.second);
+    return std::less<>()(std::get<1>(lhs), std::get<1>(rhs));
   }
 };
 
diff --git a/llvm/unittests/ADT/STLExtrasTest.cpp b/llvm/unittests/ADT/STLExtrasTest.cpp
--- a/llvm/unittests/ADT/STLExtrasTest.cpp
+++ b/llvm/unittests/ADT/STLExtrasTest.cpp
@@ -14,6 +14,8 @@
 #include <array>
 #include <climits>
 #include <list>
+#include <tuple>
+#include <utility>
 #include <vector>
 
 using namespace llvm;
@@ -1055,4 +1057,36 @@
                 "addEnumValues(ULongLongMax, C::Two) failed.");
 }
 
+TEST(STLExtrasTest, LessFirst) {
+  {
+    std::pair<int, int> A(0, 1);
+    std::pair<int, int> B(1, 0);
+    EXPECT_TRUE(less_first()(A, B));
+    EXPECT_FALSE(less_first()(B, A));
+  }
+
+  {
+    std::tuple<int, int> A(0, 1);
+    std::tuple<int, int> B(1, 0);
+    EXPECT_TRUE(less_first()(A, B));
+    EXPECT_FALSE(less_first()(B, A));
+  }
+}
+
+TEST(STLExtrasTest, LessSecond) {
+  {
+    std::pair<int, int> A(0, 1);
+    std::pair<int, int> B(1, 0);
+    EXPECT_FALSE(less_second()(A, B));
+    EXPECT_TRUE(less_second()(B, A));
+  }
+
+  {
+    std::tuple<int, int> A(0, 1);
+    std::tuple<int, int> B(1, 0);
+    EXPECT_FALSE(less_second()(A, B));
+    EXPECT_TRUE(less_second()(B, A));
+  }
+}
+
 } // namespace