Index: test/std/depr/depr.c.headers/math_h.pass.cpp
===================================================================
--- test/std/depr/depr.c.headers/math_h.pass.cpp
+++ test/std/depr/depr.c.headers/math_h.pass.cpp
@@ -9,9 +9,6 @@
 
 // <math.h>
 
-// NOTE: isinf and isnan are tested separately because they are expected to fail
-// on linux. We don't want their expected failure to hide other failures in this file.
-
 #include <math.h>
 #include <type_traits>
 #include <cassert>
@@ -631,6 +628,29 @@
     assert(isgreaterequal(-1.0, 0.F) == false);
 }
 
+void test_isinf()
+{
+#ifdef isinf
+#error isinf defined
+#endif
+    static_assert((std::is_same<decltype(isinf((float)0)), bool>::value), "");
+
+    typedef decltype(isinf((double)0)) DoubleRetType;
+#ifndef __linux__
+    static_assert((std::is_same<DoubleRetType, bool>::value), "");
+#else
+    // GLIBC < 2.26 defines 'isinf(double)' with a return type of 'int' in
+    // all C++ dialects. The test should tolerate this.
+    // See: https://sourceware.org/bugzilla/show_bug.cgi?id=19439
+    static_assert((std::is_same<DoubleRetType, bool>::value
+                || std::is_same<DoubleRetType, int>::value), "");
+#endif
+
+    static_assert((std::is_same<decltype(isinf(0)), bool>::value), "");
+    static_assert((std::is_same<decltype(isinf((long double)0)), bool>::value), "");
+    assert(isinf(-1.0) == false);
+}
+
 void test_isless()
 {
 #ifdef isless
@@ -688,6 +708,29 @@
     assert(islessgreater(-1.0, 0.F) == true);
 }
 
+void test_isnan()
+{
+#ifdef isnan
+#error isnan defined
+#endif
+    static_assert((std::is_same<decltype(isnan((float)0)), bool>::value), "");
+
+    typedef decltype(isnan((double)0)) DoubleRetType;
+#ifndef __linux__
+    static_assert((std::is_same<DoubleRetType, bool>::value), "");
+#else
+    // GLIBC < 2.26 defines 'isnan(double)' with a return type of 'int' in
+    // all C++ dialects. The test should tolerate this.
+    // See: https://sourceware.org/bugzilla/show_bug.cgi?id=19439
+    static_assert((std::is_same<DoubleRetType, bool>::value
+                || std::is_same<DoubleRetType, int>::value), "");
+#endif
+
+    static_assert((std::is_same<decltype(isnan(0)), bool>::value), "");
+    static_assert((std::is_same<decltype(isnan((long double)0)), bool>::value), "");
+    assert(isnan(-1.0) == false);
+}
+
 void test_isunordered()
 {
 #ifdef isunordered
@@ -1443,9 +1486,11 @@
     test_isnormal();
     test_isgreater();
     test_isgreaterequal();
+    test_isinf();
     test_isless();
     test_islessequal();
     test_islessgreater();
+    test_isnan();
     test_isunordered();
     test_acosh();
     test_asinh();
Index: test/std/depr/depr.c.headers/math_h_isinf.pass.cpp
===================================================================
--- test/std/depr/depr.c.headers/math_h_isinf.pass.cpp
+++ /dev/null
@@ -1,30 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is dual licensed under the MIT and the University of Illinois Open
-// Source Licenses. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-// <math.h>
-
-// isinf
-
-// XFAIL: linux
-
-#include <math.h>
-#include <type_traits>
-#include <cassert>
-
-int main()
-{
-#ifdef isinf
-#error isinf defined
-#endif
-    static_assert((std::is_same<decltype(isinf((float)0)), bool>::value), "");
-    static_assert((std::is_same<decltype(isinf((double)0)), bool>::value), "");
-    static_assert((std::is_same<decltype(isinf(0)), bool>::value), "");
-    static_assert((std::is_same<decltype(isinf((long double)0)), bool>::value), "");
-    assert(isinf(-1.0) == false);
-}
Index: test/std/depr/depr.c.headers/math_h_isnan.pass.cpp
===================================================================
--- test/std/depr/depr.c.headers/math_h_isnan.pass.cpp
+++ /dev/null
@@ -1,30 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is dual licensed under the MIT and the University of Illinois Open
-// Source Licenses. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-// <math.h>
-
-// isnan
-
-// XFAIL: linux
-
-#include <math.h>
-#include <type_traits>
-#include <cassert>
-
-int main()
-{
-#ifdef isnan
-#error isnan defined
-#endif
-    static_assert((std::is_same<decltype(isnan((float)0)), bool>::value), "");
-    static_assert((std::is_same<decltype(isnan((double)0)), bool>::value), "");
-    static_assert((std::is_same<decltype(isnan(0)), bool>::value), "");
-    static_assert((std::is_same<decltype(isnan((long double)0)), bool>::value), "");
-    assert(isnan(-1.0) == false);
-}
Index: test/std/numerics/c.math/cmath.pass.cpp
===================================================================
--- test/std/numerics/c.math/cmath.pass.cpp
+++ test/std/numerics/c.math/cmath.pass.cpp
@@ -9,9 +9,6 @@
 
 // <cmath>
 
-// NOTE: isinf and isnan are tested separately because they are expected to fail
-// on linux. We don't want their expected failure to hide other failures in this file.
-
 #include <cmath>
 #include <type_traits>
 #include <cassert>
@@ -631,6 +628,29 @@
     assert(std::isgreaterequal(-1.0, 0.F) == false);
 }
 
+void test_isinf()
+{
+#ifdef isinf
+#error isinf defined
+#endif
+    static_assert((std::is_same<decltype(std::isinf((float)0)), bool>::value), "");
+
+    typedef decltype(std::isinf((double)0)) DoubleRetType;
+#ifndef __linux__
+    static_assert((std::is_same<DoubleRetType, bool>::value), "");
+#else
+    // GLIBC < 2.26 defines 'isinf(double)' with a return type of 'int' in
+    // all C++ dialects. The test should tolerate this.
+    // See: https://sourceware.org/bugzilla/show_bug.cgi?id=19439
+    static_assert((std::is_same<DoubleRetType, bool>::value
+                || std::is_same<DoubleRetType, int>::value), "");
+#endif
+
+    static_assert((std::is_same<decltype(std::isinf(0)), bool>::value), "");
+    static_assert((std::is_same<decltype(std::isinf((long double)0)), bool>::value), "");
+    assert(std::isinf(-1.0) == false);
+}
+
 void test_isless()
 {
 #ifdef isless
@@ -688,6 +708,29 @@
     assert(std::islessgreater(-1.0, 0.F) == true);
 }
 
+void test_isnan()
+{
+#ifdef isnan
+#error isnan defined
+#endif
+    static_assert((std::is_same<decltype(std::isnan((float)0)), bool>::value), "");
+
+    typedef decltype(std::isnan((double)0)) DoubleRetType;
+#ifndef __linux__
+    static_assert((std::is_same<DoubleRetType, bool>::value), "");
+#else
+    // GLIBC < 2.26 defines 'isnan(double)' with a return type of 'int' in
+    // all C++ dialects. The test should tolerate this.
+    // See: https://sourceware.org/bugzilla/show_bug.cgi?id=19439
+    static_assert((std::is_same<DoubleRetType, bool>::value
+                || std::is_same<DoubleRetType, int>::value), "");
+#endif
+
+    static_assert((std::is_same<decltype(std::isnan(0)), bool>::value), "");
+    static_assert((std::is_same<decltype(std::isnan((long double)0)), bool>::value), "");
+    assert(std::isnan(-1.0) == false);
+}
+
 void test_isunordered()
 {
 #ifdef isunordered
@@ -1443,9 +1486,11 @@
     test_isnormal();
     test_isgreater();
     test_isgreaterequal();
+    test_isinf();
     test_isless();
     test_islessequal();
     test_islessgreater();
+    test_isnan();
     test_isunordered();
     test_acosh();
     test_asinh();
Index: test/std/numerics/c.math/cmath_isinf.pass.cpp
===================================================================
--- test/std/numerics/c.math/cmath_isinf.pass.cpp
+++ /dev/null
@@ -1,30 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is dual licensed under the MIT and the University of Illinois Open
-// Source Licenses. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-// <cmath>
-
-// isinf
-
-// XFAIL: linux
-
-#include <cmath>
-#include <type_traits>
-#include <cassert>
-
-int main()
-{
-#ifdef isinf
-#error isinf defined
-#endif
-    static_assert((std::is_same<decltype(std::isinf((float)0)), bool>::value), "");
-    static_assert((std::is_same<decltype(std::isinf((double)0)), bool>::value), "");
-    static_assert((std::is_same<decltype(std::isinf(0)), bool>::value), "");
-    static_assert((std::is_same<decltype(std::isinf((long double)0)), bool>::value), "");
-    assert(std::isinf(-1.0) == false);
-}
\ No newline at end of file
Index: test/std/numerics/c.math/cmath_isnan.pass.cpp
===================================================================
--- test/std/numerics/c.math/cmath_isnan.pass.cpp
+++ /dev/null
@@ -1,30 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is dual licensed under the MIT and the University of Illinois Open
-// Source Licenses. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-// <cmath>
-
-// isnan
-
-// XFAIL: linux
-
-#include <cmath>
-#include <type_traits>
-#include <cassert>
-
-int main()
-{
-#ifdef isnan
-#error isnan defined
-#endif
-    static_assert((std::is_same<decltype(std::isnan((float)0)), bool>::value), "");
-    static_assert((std::is_same<decltype(std::isnan((double)0)), bool>::value), "");
-    static_assert((std::is_same<decltype(std::isnan(0)), bool>::value), "");
-    static_assert((std::is_same<decltype(std::isnan((long double)0)), bool>::value), "");
-    assert(std::isnan(-1.0) == false);
-}