Index: include/locale
===================================================================
--- include/locale
+++ include/locale
@@ -1402,6 +1402,7 @@
     this->__format_int(__fmt+1, __len, true, __iob.flags());
     const unsigned __nbuf = (numeric_limits<long>::digits / 3)
                           + ((numeric_limits<long>::digits % 3) != 0)
+                          + ((__iob.flags() & ios_base::showbase) != 0)
                           + 2;
     char __nar[__nbuf];
     int __nc = __libcpp_snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
@@ -1428,6 +1429,7 @@
     this->__format_int(__fmt+1, __len, true, __iob.flags());
     const unsigned __nbuf = (numeric_limits<long long>::digits / 3)
                           + ((numeric_limits<long long>::digits % 3) != 0)
+                          + ((__iob.flags() & ios_base::showbase) != 0)
                           + 2;
     char __nar[__nbuf];
     int __nc = __libcpp_snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
@@ -1454,6 +1456,7 @@
     this->__format_int(__fmt+1, __len, false, __iob.flags());
     const unsigned __nbuf = (numeric_limits<unsigned long>::digits / 3)
                           + ((numeric_limits<unsigned long>::digits % 3) != 0)
+                          + ((__iob.flags() & ios_base::showbase) != 0)
                           + 1;
     char __nar[__nbuf];
     int __nc = __libcpp_snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
@@ -1480,6 +1483,7 @@
     this->__format_int(__fmt+1, __len, false, __iob.flags());
     const unsigned __nbuf = (numeric_limits<unsigned long long>::digits / 3)
                           + ((numeric_limits<unsigned long long>::digits % 3) != 0)
+                          + ((__iob.flags() & ios_base::showbase) != 0)
                           + 1;
     char __nar[__nbuf];
     int __nc = __libcpp_snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
Index: test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/minmax_showbase.pass.cpp
===================================================================
--- /dev/null
+++ test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/minmax_showbase.pass.cpp
@@ -0,0 +1,97 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <ostream>
+
+// template <class charT, class traits = char_traits<charT> >
+//   class basic_ostream;
+
+// operator<<(short n);
+// operator<<(unsigned short n);
+// operator<<(int n);
+// operator<<(unsigned int n);
+// operator<<(long n);
+// operator<<(unsigned long n);
+// operator<<(long long n);
+// operator<<(unsigned long long n);
+
+//  Testing to make sure that the max length values are correctly inserted when
+//  using std::showbase
+
+#include <cassert>
+#include <cstdint>
+#include <ios>
+#include <limits>
+#include <sstream>
+#include <type_traits>
+
+template <typename T>
+static void test(std::ios_base::fmtflags fmt, const char *expected)
+{
+    std::stringstream ss;
+    ss.setf(fmt, std::ios_base::basefield);
+    ss << std::showbase << (std::is_signed<T>::value ? std::numeric_limits<T>::min() : std::numeric_limits<T>::max());
+    assert(ss.str() == expected);
+}
+
+int main(void)
+{
+    const std::ios_base::fmtflags o = std::ios_base::oct;
+    const std::ios_base::fmtflags d = std::ios_base::dec;
+    const std::ios_base::fmtflags x = std::ios_base::hex;
+
+    test<short>(o, "0100000");
+    test<short>(d, "-32768");
+    test<short>(x, "0x8000");
+
+    test<unsigned short>(o, "0177777");
+    test<unsigned short>(d, "65535");
+    test<unsigned short>(x, "0xffff");
+
+    test<int>(o, "020000000000");
+    test<int>(d, "-2147483648");
+    test<int>(x, "0x80000000");
+
+    test<unsigned int>(o, "037777777777");
+    test<unsigned int>(d, "4294967295");
+    test<unsigned int>(x, "0xffffffff");
+
+    const bool long_is_32 = std::integral_constant<bool, sizeof(long) == sizeof(int32_t)>::value; // avoid compiler warnings
+    const bool long_is_64 = std::integral_constant<bool, sizeof(long) == sizeof(int64_t)>::value; // avoid compiler warnings
+    const bool long_long_is_64 = std::integral_constant<bool, sizeof(long long) == sizeof(int64_t)>::value; // avoid compiler warnings
+
+    if (long_is_32) {
+        test<long>(o, "020000000000");
+        test<long>(d, "-2147483648");
+        test<long>(x, "0x80000000");
+
+        test<unsigned long>(o, "037777777777");
+        test<unsigned long>(d, "4294967295");
+        test<unsigned long>(x, "0xffffffff");
+    } else if (long_is_64) {
+        test<long>(o, "01000000000000000000000");
+        test<long>(d, "-9223372036854775808");
+        test<long>(x, "0x8000000000000000");
+
+        test<unsigned long>(o, "01777777777777777777777");
+        test<unsigned long>(d, "18446744073709551615");
+        test<unsigned long>(x, "0xffffffffffffffff");
+    }
+    if (long_long_is_64) {
+        test<long long>(o, "01000000000000000000000");
+        test<long long>(d, "-9223372036854775808");
+        test<long long>(x, "0x8000000000000000");
+
+        test<unsigned long long>(o, "01777777777777777777777");
+        test<unsigned long long>(d, "18446744073709551615");
+        test<unsigned long long>(x, "0xffffffffffffffff");
+    }
+
+    return 0;
+}