diff --git a/clang-tools-extra/clangd/index/CanonicalIncludes.h b/clang-tools-extra/clangd/index/CanonicalIncludes.h
--- a/clang-tools-extra/clangd/index/CanonicalIncludes.h
+++ b/clang-tools-extra/clangd/index/CanonicalIncludes.h
@@ -57,9 +57,6 @@
 private:
   /// A map from full include path to a canonical path.
   llvm::StringMap<std::string> FullPathMapping;
-  /// A map from a suffix (one or components of a path) to a canonical path.
-  /// Used only for mapping standard headers.
-  const llvm::StringMap<llvm::StringRef> *StdSuffixHeaderMapping = nullptr;
   /// A map from fully qualified symbol names to header names.
   /// Used only for mapping standard symbols.
   const llvm::StringMap<llvm::StringRef> *StdSymbolMapping = nullptr;
diff --git a/clang-tools-extra/clangd/index/CanonicalIncludes.cpp b/clang-tools-extra/clangd/index/CanonicalIncludes.cpp
--- a/clang-tools-extra/clangd/index/CanonicalIncludes.cpp
+++ b/clang-tools-extra/clangd/index/CanonicalIncludes.cpp
@@ -24,10 +24,6 @@
   FullPathMapping[Path] = std::string(CanonicalPath);
 }
 
-/// The maximum number of path components in a key from StdSuffixHeaderMapping.
-/// Used to minimize the number of lookups in suffix path mappings.
-constexpr int MaxSuffixComponents = 3;
-
 llvm::StringRef
 CanonicalIncludes::mapHeader(llvm::StringRef Header,
                              llvm::StringRef QualifiedName) const {
@@ -41,21 +37,6 @@
   auto MapIt = FullPathMapping.find(Header);
   if (MapIt != FullPathMapping.end())
     return MapIt->second;
-
-  if (!StdSuffixHeaderMapping)
-    return Header;
-
-  int Components = 1;
-
-  // FIXME: check that this works on Windows and add tests.
-  for (auto It = llvm::sys::path::rbegin(Header),
-            End = llvm::sys::path::rend(Header);
-       It != End && Components <= MaxSuffixComponents; ++It, ++Components) {
-    auto SubPath = Header.substr(It->data() - Header.begin());
-    auto MappingIt = StdSuffixHeaderMapping->find(SubPath);
-    if (MappingIt != StdSuffixHeaderMapping->end())
-      return MappingIt->second;
-  }
   return Header;
 }
 
@@ -101,681 +82,6 @@
     });
     StdSymbolMapping = CSymbols;
   }
-
-  // FIXME: remove the std header mapping once we support ambiguous symbols, now
-  // it serves as a fallback to disambiguate:
-  //   - symbols with multiple headers (e.g. std::move)
-  static const auto *SystemHeaderMap = new llvm::StringMap<llvm::StringRef>({
-      {"include/__stddef_max_align_t.h", "<cstddef>"},
-      {"include/__wmmintrin_aes.h", "<wmmintrin.h>"},
-      {"include/__wmmintrin_pclmul.h", "<wmmintrin.h>"},
-      {"include/adxintrin.h", "<immintrin.h>"},
-      {"include/ammintrin.h", "<ammintrin.h>"},
-      {"include/avx2intrin.h", "<immintrin.h>"},
-      {"include/avx512bwintrin.h", "<immintrin.h>"},
-      {"include/avx512cdintrin.h", "<immintrin.h>"},
-      {"include/avx512dqintrin.h", "<immintrin.h>"},
-      {"include/avx512erintrin.h", "<immintrin.h>"},
-      {"include/avx512fintrin.h", "<immintrin.h>"},
-      {"include/avx512ifmaintrin.h", "<immintrin.h>"},
-      {"include/avx512ifmavlintrin.h", "<immintrin.h>"},
-      {"include/avx512pfintrin.h", "<immintrin.h>"},
-      {"include/avx512vbmiintrin.h", "<immintrin.h>"},
-      {"include/avx512vbmivlintrin.h", "<immintrin.h>"},
-      {"include/avx512vlbwintrin.h", "<immintrin.h>"},
-      {"include/avx512vlcdintrin.h", "<immintrin.h>"},
-      {"include/avx512vldqintrin.h", "<immintrin.h>"},
-      {"include/avx512vlintrin.h", "<immintrin.h>"},
-      {"include/avxintrin.h", "<immintrin.h>"},
-      {"include/bmi2intrin.h", "<x86intrin.h>"},
-      {"include/bmiintrin.h", "<x86intrin.h>"},
-      {"include/emmintrin.h", "<emmintrin.h>"},
-      {"include/f16cintrin.h", "<emmintrin.h>"},
-      {"include/float.h", "<cfloat>"},
-      {"include/fma4intrin.h", "<x86intrin.h>"},
-      {"include/fmaintrin.h", "<immintrin.h>"},
-      {"include/fxsrintrin.h", "<immintrin.h>"},
-      {"include/ia32intrin.h", "<x86intrin.h>"},
-      {"include/immintrin.h", "<immintrin.h>"},
-      {"include/inttypes.h", "<cinttypes>"},
-      {"include/limits.h", "<climits>"},
-      {"include/lzcntintrin.h", "<x86intrin.h>"},
-      {"include/mm3dnow.h", "<mm3dnow.h>"},
-      {"include/mm_malloc.h", "<mm_malloc.h>"},
-      {"include/mmintrin.h", "<mmintrin>"},
-      {"include/mwaitxintrin.h", "<x86intrin.h>"},
-      {"include/pkuintrin.h", "<immintrin.h>"},
-      {"include/pmmintrin.h", "<pmmintrin.h>"},
-      {"include/popcntintrin.h", "<popcntintrin.h>"},
-      {"include/prfchwintrin.h", "<x86intrin.h>"},
-      {"include/rdseedintrin.h", "<x86intrin.h>"},
-      {"include/rtmintrin.h", "<immintrin.h>"},
-      {"include/shaintrin.h", "<immintrin.h>"},
-      {"include/smmintrin.h", "<smmintrin.h>"},
-      {"include/stdalign.h", "<cstdalign>"},
-      {"include/stdarg.h", "<cstdarg>"},
-      {"include/stdbool.h", "<cstdbool>"},
-      {"include/stddef.h", "<cstddef>"},
-      {"include/stdint.h", "<cstdint>"},
-      {"include/tbmintrin.h", "<x86intrin.h>"},
-      {"include/tmmintrin.h", "<tmmintrin.h>"},
-      {"include/wmmintrin.h", "<wmmintrin.h>"},
-      {"include/x86intrin.h", "<x86intrin.h>"},
-      {"include/xmmintrin.h", "<xmmintrin.h>"},
-      {"include/xopintrin.h", "<x86intrin.h>"},
-      {"include/xsavecintrin.h", "<immintrin.h>"},
-      {"include/xsaveintrin.h", "<immintrin.h>"},
-      {"include/xsaveoptintrin.h", "<immintrin.h>"},
-      {"include/xsavesintrin.h", "<immintrin.h>"},
-      {"include/xtestintrin.h", "<immintrin.h>"},
-      {"include/_G_config.h", "<cstdio>"},
-      {"include/assert.h", "<cassert>"},
-      {"algorithm", "<algorithm>"},
-      {"valarray", "<valarray>"},
-      {"array", "<array>"},
-      {"atomic", "<atomic>"},
-      {"backward/auto_ptr.h", "<memory>"},
-      {"backward/binders.h", "<string>"},
-      {"bits/algorithmfwd.h", "<algorithm>"},
-      {"bits/alloc_traits.h", "<memory>"},
-      {"bits/allocated_ptr.h", "<memory>"},
-      {"bits/allocator.h", "<allocator>"},
-      {"bits/atomic_base.h", "<atomic>"},
-      {"bits/atomic_lockfree_defines.h", "<exception>"},
-      {"bits/atomic_futex.h", "<atomic>"},
-      {"bits/basic_ios.h", "<ios>"},
-      {"bits/basic_ios.tcc", "<ios>"},
-      {"bits/basic_string.h", "<string>"},
-      {"bits/basic_string.tcc", "<string>"},
-      {"bits/char_traits.h", "<string>"},
-      {"bits/codecvt.h", "<locale>"},
-      {"bits/concept_check.h", "<numeric>"},
-      {"bits/cpp_type_traits.h", "<cmath>"},
-      {"bits/cxxabi_forced.h", "<cxxabi.h>"},
-      {"bits/deque.tcc", "<deque>"},
-      {"bits/exception.h", "<exception>"},
-      {"bits/exception_defines.h", "<exception>"},
-      {"bits/exception_ptr.h", "<exception>"},
-      {"bits/forward_list.h", "<forward_list>"},
-      {"bits/forward_list.tcc", "<forward_list>"},
-      {"bits/fstream.tcc", "<fstream>"},
-      {"bits/functexcept.h", "<list>"},
-      {"bits/functional_hash.h", "<functional>"},
-      {"bits/gslice.h", "<valarray>"},
-      {"bits/gslice_array.h", "<valarray>"},
-      {"bits/hash_bytes.h", "<typeinfo>"},
-      {"bits/hashtable.h", "<unordered_set>"},
-      {"bits/hashtable_policy.h", "<unordered_set>"},
-      {"bits/indirect_array.h", "<valarray>"},
-      {"bits/invoke.h", "<functional>"},
-      {"bits/ios_base.h", "<ios>"},
-      {"bits/istream.tcc", "<istream>"},
-      {"bits/list.tcc", "<list>"},
-      {"bits/locale_classes.h", "<locale>"},
-      {"bits/locale_classes.tcc", "<locale>"},
-      {"bits/locale_conv.h", "<locale>"},
-      {"bits/locale_facets.h", "<locale>"},
-      {"bits/locale_facets.tcc", "<locale>"},
-      {"bits/locale_facets_nonio.h", "<locale>"},
-      {"bits/locale_facets_nonio.tcc", "<locale>"},
-      {"bits/localefwd.h", "<locale>"},
-      {"bits/mask_array.h", "<valarray>"},
-      {"bits/memoryfwd.h", "<memory>"},
-      {"bits/move.h", "<utility>"},
-      {"bits/nested_exception.h", "<exception>"},
-      {"bits/ostream.tcc", "<ostream>"},
-      {"bits/ostream_insert.h", "<ostream>"},
-      {"bits/parse_numbers.h", "<chrono>"},
-      {"bits/postypes.h", "<ios>"},
-      {"bits/predefined_ops.h", "<algorithm>"},
-      {"bits/ptr_traits.h", "<memory>"},
-      {"bits/quoted_string.h", "<iomanip>"},
-      {"bits/random.h", "<random>"},
-      {"bits/random.tcc", "<random>"},
-      {"bits/range_access.h", "<iterator>"},
-      {"bits/refwrap.h", "<functional>"},
-      {"bits/regex.h", "<regex>"},
-      {"bits/regex_automaton.h", "<regex>"},
-      {"bits/regex_compiler.h", "<regex>"},
-      {"bits/regex_constants.h", "<regex>"},
-      {"bits/regex_cursor.h", "<regex>"},
-      {"bits/regex_error.h", "<regex>"},
-      {"bits/regex_executor.h", "<regex>"},
-      {"bits/regex_grep_matcher.h", "<regex>"},
-      {"bits/regex_grep_matcher.tcc", "<regex>"},
-      {"bits/regex_nfa.h", "<regex>"},
-      {"bits/regex_scanner.h", "<regex>"},
-      {"bits/shared_ptr.h", "<memory>"},
-      {"bits/shared_ptr_base.h", "<memory>"},
-      {"bits/shared_ptr_atomic.h", "<atomic>"},
-      {"bits/slice_array.h", "<valarray>"},
-      {"bits/sstream.tcc", "<sstream>"},
-      {"bits/std_abs.h", "<cmath>"},
-      {"bits/std_function.h", "<functional>"},
-      {"bits/std_mutex.h", "<mutex>"},
-      {"bits/stl_algo.h", "<algorithm>"},
-      {"bits/stl_algobase.h", "<algorithm>"},
-      {"bits/stl_bvector.h", "<vector>"},
-      {"bits/stl_construct.h", "<deque>"},
-      {"bits/stl_deque.h", "<deque>"},
-      {"bits/stl_function.h", "<functional>"},
-      {"bits/stl_heap.h", "<heap>"},
-      {"bits/stl_iterator.h", "<iterator>"},
-      {"bits/stl_iterator_base_funcs.h", "<iterator>"},
-      {"bits/stl_iterator_base_types.h", "<iterator>"},
-      {"bits/stl_list.h", "<list>"},
-      {"bits/stl_map.h", "<map>"},
-      {"bits/stl_multimap.h", "<map>"},
-      {"bits/stl_multiset.h", "<set>"},
-      {"bits/stl_numeric.h", "<numeric>"},
-      {"bits/stl_pair.h", "<utility>"},
-      {"bits/stl_queue.h", "<queue>"},
-      {"bits/stl_raw_storage_iter.h", "<memory>"},
-      {"bits/stl_relops.h", "<utility>"},
-      {"bits/stl_set.h", "<set>"},
-      {"bits/stl_stack.h", "<stack>"},
-      {"bits/stl_tempbuf.h", "<memory>"},
-      {"bits/stl_tree.h", "<map>"},
-      {"bits/stl_uninitialized.h", "<memory>"},
-      {"bits/stl_vector.h", "<vector>"},
-      {"bits/stream_iterator.h", "<iterator>"},
-      {"bits/streambuf.tcc", "<streambuf>"},
-      {"bits/streambuf_iterator.h", "<iterator>"},
-      {"bits/stringfwd.h", "<string>"},
-      {"bits/uniform_int_dist.h", "<random>"},
-      {"bits/unique_ptr.h", "<memory>"},
-      {"bits/unordered_map.h", "<unordered_map>"},
-      {"bits/unordered_set.h", "<unordered_set>"},
-      {"bits/uses_allocator.h", "<memory>"},
-      {"bits/valarray_after.h", "<valarray>"},
-      {"bits/valarray_array.h", "<valarray>"},
-      {"bits/valarray_array.tcc", "<valarray>"},
-      {"bits/valarray_before.h", "<valarray>"},
-      {"bits/vector.tcc", "<vector>"},
-      {"bitset", "<bitset>"},
-      {"ccomplex", "<ccomplex>"},
-      {"cctype", "<cctype>"},
-      {"cerrno", "<cerrno>"},
-      {"cfenv", "<cfenv>"},
-      {"cfloat", "<cfloat>"},
-      {"chrono", "<chrono>"},
-      {"cinttypes", "<cinttypes>"},
-      {"climits", "<climits>"},
-      {"clocale", "<clocale>"},
-      {"cmath", "<cmath>"},
-      {"complex", "<complex>"},
-      {"complex.h", "<complex.h>"},
-      {"condition_variable", "<condition_variable>"},
-      {"csetjmp", "<csetjmp>"},
-      {"csignal", "<csignal>"},
-      {"cstdalign", "<cstdalign>"},
-      {"cstdarg", "<cstdarg>"},
-      {"cstdbool", "<cstdbool>"},
-      {"cstdint", "<cstdint>"},
-      {"cstdio", "<cstdio>"},
-      {"cstdlib", "<cstdlib>"},
-      {"cstring", "<cstring>"},
-      {"ctgmath", "<ctgmath>"},
-      {"ctime", "<ctime>"},
-      {"cwchar", "<cwchar>"},
-      {"cwctype", "<cwctype>"},
-      {"cxxabi.h", "<cxxabi.h>"},
-      {"debug/debug.h", "<numeric>"},
-      {"debug/map.h", "<map>"},
-      {"debug/multimap.h", "<multimap>"},
-      {"debug/multiset.h", "<multiset>"},
-      {"debug/set.h", "<set>"},
-      {"deque", "<deque>"},
-      {"exception", "<exception>"},
-      {"ext/alloc_traits.h", "<deque>"},
-      {"ext/atomicity.h", "<memory>"},
-      {"ext/concurrence.h", "<memory>"},
-      {"ext/new_allocator.h", "<string>"},
-      {"ext/numeric_traits.h", "<list>"},
-      {"ext/string_conversions.h", "<string>"},
-      {"ext/type_traits.h", "<cmath>"},
-      {"fenv.h", "<fenv.h>"},
-      {"forward_list", "<forward_list>"},
-      {"fstream", "<fstream>"},
-      {"functional", "<functional>"},
-      {"future", "<future>"},
-      {"initializer_list", "<initializer_list>"},
-      {"iomanip", "<iomanip>"},
-      {"ios", "<ios>"},
-      {"iosfwd", "<iosfwd>"},
-      {"iostream", "<iostream>"},
-      {"istream", "<istream>"},
-      {"iterator", "<iterator>"},
-      {"limits", "<limits>"},
-      {"list", "<list>"},
-      {"locale", "<locale>"},
-      {"map", "<map>"},
-      {"memory", "<memory>"},
-      {"shared_mutex", "<shared_mutex>"},
-      {"mutex", "<mutex>"},
-      {"new", "<new>"},
-      {"numeric", "<numeric>"},
-      {"ostream", "<ostream>"},
-      {"queue", "<queue>"},
-      {"random", "<random>"},
-      {"ratio", "<ratio>"},
-      {"regex", "<regex>"},
-      {"scoped_allocator", "<scoped_allocator>"},
-      {"set", "<set>"},
-      {"sstream", "<sstream>"},
-      {"stack", "<stack>"},
-      {"stdexcept", "<stdexcept>"},
-      {"streambuf", "<streambuf>"},
-      {"string", "<string>"},
-      {"system_error", "<system_error>"},
-      {"tgmath.h", "<tgmath.h>"},
-      {"thread", "<thread>"},
-      {"tuple", "<tuple>"},
-      {"type_traits", "<type_traits>"},
-      {"typeindex", "<typeindex>"},
-      {"typeinfo", "<typeinfo>"},
-      {"unordered_map", "<unordered_map>"},
-      {"unordered_set", "<unordered_set>"},
-      {"utility", "<utility>"},
-      {"valarray", "<valarray>"},
-      {"vector", "<vector>"},
-      {"include/complex.h", "<complex.h>"},
-      {"include/ctype.h", "<cctype>"},
-      {"include/errno.h", "<cerrno>"},
-      {"include/fenv.h", "<fenv.h>"},
-      {"include/inttypes.h", "<cinttypes>"},
-      {"include/libio.h", "<cstdio>"},
-      {"include/limits.h", "<climits>"},
-      {"include/locale.h", "<clocale>"},
-      {"include/math.h", "<cmath>"},
-      {"include/setjmp.h", "<csetjmp>"},
-      {"include/signal.h", "<csignal>"},
-      {"include/stdint.h", "<cstdint>"},
-      {"include/stdio.h", "<cstdio>"},
-      {"include/stdlib.h", "<cstdlib>"},
-      {"include/string.h", "<cstring>"},
-      {"include/time.h", "<ctime>"},
-      {"include/wchar.h", "<cwchar>"},
-      {"include/wctype.h", "<cwctype>"},
-      {"bits/cmathcalls.h", "<complex.h>"},
-      {"bits/errno.h", "<cerrno>"},
-      {"bits/fenv.h", "<fenv.h>"},
-      {"bits/huge_val.h", "<cmath>"},
-      {"bits/huge_valf.h", "<cmath>"},
-      {"bits/huge_vall.h", "<cmath>"},
-      {"bits/inf.h", "<cmath>"},
-      {"bits/local_lim.h", "<climits>"},
-      {"bits/locale.h", "<clocale>"},
-      {"bits/mathcalls.h", "<math.h>"},
-      {"bits/mathdef.h", "<cmath>"},
-      {"bits/nan.h", "<cmath>"},
-      {"bits/posix1_lim.h", "<climits>"},
-      {"bits/posix2_lim.h", "<climits>"},
-      {"bits/setjmp.h", "<csetjmp>"},
-      {"bits/sigaction.h", "<csignal>"},
-      {"bits/sigcontext.h", "<csignal>"},
-      {"bits/siginfo.h", "<csignal>"},
-      {"bits/signum.h", "<csignal>"},
-      {"bits/sigset.h", "<csignal>"},
-      {"bits/sigstack.h", "<csignal>"},
-      {"bits/stdio_lim.h", "<cstdio>"},
-      {"bits/sys_errlist.h", "<cstdio>"},
-      {"bits/time.h", "<ctime>"},
-      {"bits/timex.h", "<ctime>"},
-      {"bits/typesizes.h", "<cstdio>"},
-      {"bits/wchar.h", "<cwchar>"},
-      {"bits/wordsize.h", "<csetjmp>"},
-      {"bits/xopen_lim.h", "<climits>"},
-      {"include/xlocale.h", "<cstring>"},
-      {"bits/atomic_word.h", "<memory>"},
-      {"bits/basic_file.h", "<fstream>"},
-      {"bits/c\\+\\+allocator.h", "<string>"},
-      {"bits/c\\+\\+config.h", "<cstddef>"},
-      {"bits/c\\+\\+io.h", "<ios>"},
-      {"bits/c\\+\\+locale.h", "<locale>"},
-      {"bits/cpu_defines.h", "<iosfwd>"},
-      {"bits/ctype_base.h", "<locale>"},
-      {"bits/cxxabi_tweaks.h", "<cxxabi.h>"},
-      {"bits/error_constants.h", "<system_error>"},
-      {"bits/gthr-default.h", "<memory>"},
-      {"bits/gthr.h", "<memory>"},
-      {"bits/opt_random.h", "<random>"},
-      {"bits/os_defines.h", "<iosfwd>"},
-      // GNU C headers
-      {"include/aio.h", "<aio.h>"},
-      {"include/aliases.h", "<aliases.h>"},
-      {"include/alloca.h", "<alloca.h>"},
-      {"include/ar.h", "<ar.h>"},
-      {"include/argp.h", "<argp.h>"},
-      {"include/argz.h", "<argz.h>"},
-      {"include/arpa/nameser.h", "<resolv.h>"},
-      {"include/arpa/nameser_compat.h", "<resolv.h>"},
-      {"include/byteswap.h", "<byteswap.h>"},
-      {"include/cpio.h", "<cpio.h>"},
-      {"include/crypt.h", "<crypt.h>"},
-      {"include/dirent.h", "<dirent.h>"},
-      {"include/dlfcn.h", "<dlfcn.h>"},
-      {"include/elf.h", "<elf.h>"},
-      {"include/endian.h", "<endian.h>"},
-      {"include/envz.h", "<envz.h>"},
-      {"include/err.h", "<err.h>"},
-      {"include/error.h", "<error.h>"},
-      {"include/execinfo.h", "<execinfo.h>"},
-      {"include/fcntl.h", "<fcntl.h>"},
-      {"include/features.h", "<features.h>"},
-      {"include/fenv.h", "<fenv.h>"},
-      {"include/fmtmsg.h", "<fmtmsg.h>"},
-      {"include/fnmatch.h", "<fnmatch.h>"},
-      {"include/fstab.h", "<fstab.h>"},
-      {"include/fts.h", "<fts.h>"},
-      {"include/ftw.h", "<ftw.h>"},
-      {"include/gconv.h", "<gconv.h>"},
-      {"include/getopt.h", "<getopt.h>"},
-      {"include/glob.h", "<glob.h>"},
-      {"include/grp.h", "<grp.h>"},
-      {"include/gshadow.h", "<gshadow.h>"},
-      {"include/iconv.h", "<iconv.h>"},
-      {"include/ifaddrs.h", "<ifaddrs.h>"},
-      {"include/kdb.h", "<kdb.h>"},
-      {"include/langinfo.h", "<langinfo.h>"},
-      {"include/libgen.h", "<libgen.h>"},
-      {"include/libintl.h", "<libintl.h>"},
-      {"include/link.h", "<link.h>"},
-      {"include/malloc.h", "<malloc.h>"},
-      {"include/mcheck.h", "<mcheck.h>"},
-      {"include/memory.h", "<memory.h>"},
-      {"include/mntent.h", "<mntent.h>"},
-      {"include/monetary.h", "<monetary.h>"},
-      {"include/mqueue.h", "<mqueue.h>"},
-      {"include/netdb.h", "<netdb.h>"},
-      {"include/netinet/in.h", "<netinet/in.h>"},
-      {"include/nl_types.h", "<nl_types.h>"},
-      {"include/nss.h", "<nss.h>"},
-      {"include/obstack.h", "<obstack.h>"},
-      {"include/panel.h", "<panel.h>"},
-      {"include/paths.h", "<paths.h>"},
-      {"include/printf.h", "<printf.h>"},
-      {"include/profile.h", "<profile.h>"},
-      {"include/pthread.h", "<pthread.h>"},
-      {"include/pty.h", "<pty.h>"},
-      {"include/pwd.h", "<pwd.h>"},
-      {"include/re_comp.h", "<re_comp.h>"},
-      {"include/regex.h", "<regex.h>"},
-      {"include/regexp.h", "<regexp.h>"},
-      {"include/resolv.h", "<resolv.h>"},
-      {"include/rpc/netdb.h", "<netdb.h>"},
-      {"include/sched.h", "<sched.h>"},
-      {"include/search.h", "<search.h>"},
-      {"include/semaphore.h", "<semaphore.h>"},
-      {"include/sgtty.h", "<sgtty.h>"},
-      {"include/shadow.h", "<shadow.h>"},
-      {"include/spawn.h", "<spawn.h>"},
-      {"include/stab.h", "<stab.h>"},
-      {"include/stdc-predef.h", "<stdc-predef.h>"},
-      {"include/stdio_ext.h", "<stdio_ext.h>"},
-      {"include/strings.h", "<strings.h>"},
-      {"include/stropts.h", "<stropts.h>"},
-      {"include/sudo_plugin.h", "<sudo_plugin.h>"},
-      {"include/sysexits.h", "<sysexits.h>"},
-      {"include/tar.h", "<tar.h>"},
-      {"include/tcpd.h", "<tcpd.h>"},
-      {"include/term.h", "<term.h>"},
-      {"include/term_entry.h", "<term_entry.h>"},
-      {"include/termcap.h", "<termcap.h>"},
-      {"include/termios.h", "<termios.h>"},
-      {"include/thread_db.h", "<thread_db.h>"},
-      {"include/tic.h", "<tic.h>"},
-      {"include/ttyent.h", "<ttyent.h>"},
-      {"include/uchar.h", "<uchar.h>"},
-      {"include/ucontext.h", "<ucontext.h>"},
-      {"include/ulimit.h", "<ulimit.h>"},
-      {"include/unctrl.h", "<unctrl.h>"},
-      {"include/unistd.h", "<unistd.h>"},
-      {"include/utime.h", "<utime.h>"},
-      {"include/utmp.h", "<utmp.h>"},
-      {"include/utmpx.h", "<utmpx.h>"},
-      {"include/values.h", "<values.h>"},
-      {"include/wordexp.h", "<wordexp.h>"},
-      {"fpu_control.h", "<fpu_control.h>"},
-      {"ieee754.h", "<ieee754.h>"},
-      {"include/xlocale.h", "<xlocale.h>"},
-      {"gnu/lib-names.h", "<gnu/lib-names.h>"},
-      {"gnu/libc-version.h", "<gnu/libc-version.h>"},
-      {"gnu/option-groups.h", "<gnu/option-groups.h>"},
-      {"gnu/stubs-32.h", "<gnu/stubs-32.h>"},
-      {"gnu/stubs-64.h", "<gnu/stubs-64.h>"},
-      {"gnu/stubs-x32.h", "<gnu/stubs-x32.h>"},
-      {"include/rpc/auth_des.h", "<rpc/auth_des.h>"},
-      {"include/rpc/rpc_msg.h", "<rpc/rpc_msg.h>"},
-      {"include/rpc/pmap_clnt.h", "<rpc/pmap_clnt.h>"},
-      {"include/rpc/rpc.h", "<rpc/rpc.h>"},
-      {"include/rpc/types.h", "<rpc/types.h>"},
-      {"include/rpc/auth_unix.h", "<rpc/auth_unix.h>"},
-      {"include/rpc/key_prot.h", "<rpc/key_prot.h>"},
-      {"include/rpc/pmap_prot.h", "<rpc/pmap_prot.h>"},
-      {"include/rpc/auth.h", "<rpc/auth.h>"},
-      {"include/rpc/svc_auth.h", "<rpc/svc_auth.h>"},
-      {"include/rpc/xdr.h", "<rpc/xdr.h>"},
-      {"include/rpc/pmap_rmt.h", "<rpc/pmap_rmt.h>"},
-      {"include/rpc/des_crypt.h", "<rpc/des_crypt.h>"},
-      {"include/rpc/svc.h", "<rpc/svc.h>"},
-      {"include/rpc/rpc_des.h", "<rpc/rpc_des.h>"},
-      {"include/rpc/clnt.h", "<rpc/clnt.h>"},
-      {"include/scsi/scsi.h", "<scsi/scsi.h>"},
-      {"include/scsi/sg.h", "<scsi/sg.h>"},
-      {"include/scsi/scsi_ioctl.h", "<scsi/scsi_ioctl>"},
-      {"include/netrose/rose.h", "<netrose/rose.h>"},
-      {"include/nfs/nfs.h", "<nfs/nfs.h>"},
-      {"include/netatalk/at.h", "<netatalk/at.h>"},
-      {"include/netinet/ether.h", "<netinet/ether.h>"},
-      {"include/netinet/icmp6.h", "<netinet/icmp6.h>"},
-      {"include/netinet/if_ether.h", "<netinet/if_ether.h>"},
-      {"include/netinet/if_fddi.h", "<netinet/if_fddi.h>"},
-      {"include/netinet/if_tr.h", "<netinet/if_tr.h>"},
-      {"include/netinet/igmp.h", "<netinet/igmp.h>"},
-      {"include/netinet/in.h", "<netinet/in.h>"},
-      {"include/netinet/in_systm.h", "<netinet/in_systm.h>"},
-      {"include/netinet/ip.h", "<netinet/ip.h>"},
-      {"include/netinet/ip6.h", "<netinet/ip6.h>"},
-      {"include/netinet/ip_icmp.h", "<netinet/ip_icmp.h>"},
-      {"include/netinet/tcp.h", "<netinet/tcp.h>"},
-      {"include/netinet/udp.h", "<netinet/udp.h>"},
-      {"include/netrom/netrom.h", "<netrom/netrom.h>"},
-      {"include/protocols/routed.h", "<protocols/routed.h>"},
-      {"include/protocols/rwhod.h", "<protocols/rwhod.h>"},
-      {"include/protocols/talkd.h", "<protocols/talkd.h>"},
-      {"include/protocols/timed.h", "<protocols/timed.h>"},
-      {"include/rpcsvc/klm_prot.x", "<rpcsvc/klm_prot.x>"},
-      {"include/rpcsvc/rstat.h", "<rpcsvc/rstat.h>"},
-      {"include/rpcsvc/spray.x", "<rpcsvc/spray.x>"},
-      {"include/rpcsvc/nlm_prot.x", "<rpcsvc/nlm_prot.x>"},
-      {"include/rpcsvc/nis_callback.x", "<rpcsvc/nis_callback.x>"},
-      {"include/rpcsvc/yp.h", "<rpcsvc/yp.h>"},
-      {"include/rpcsvc/yp.x", "<rpcsvc/yp.x>"},
-      {"include/rpcsvc/nfs_prot.h", "<rpcsvc/nfs_prot.h>"},
-      {"include/rpcsvc/rex.h", "<rpcsvc/rex.h>"},
-      {"include/rpcsvc/yppasswd.h", "<rpcsvc/yppasswd.h>"},
-      {"include/rpcsvc/rex.x", "<rpcsvc/rex.x>"},
-      {"include/rpcsvc/nis_tags.h", "<rpcsvc/nis_tags.h>"},
-      {"include/rpcsvc/nis_callback.h", "<rpcsvc/nis_callback.h>"},
-      {"include/rpcsvc/nfs_prot.x", "<rpcsvc/nfs_prot.x>"},
-      {"include/rpcsvc/bootparam_prot.x", "<rpcsvc/bootparam_prot.x>"},
-      {"include/rpcsvc/rusers.x", "<rpcsvc/rusers.x>"},
-      {"include/rpcsvc/rquota.x", "<rpcsvc/rquota.x>"},
-      {"include/rpcsvc/nis.h", "<rpcsvc/nis.h>"},
-      {"include/rpcsvc/nislib.h", "<rpcsvc/nislib.h>"},
-      {"include/rpcsvc/ypupd.h", "<rpcsvc/ypupd.h>"},
-      {"include/rpcsvc/bootparam.h", "<rpcsvc/bootparam.h>"},
-      {"include/rpcsvc/spray.h", "<rpcsvc/spray.h>"},
-      {"include/rpcsvc/key_prot.h", "<rpcsvc/key_prot.h>"},
-      {"include/rpcsvc/klm_prot.h", "<rpcsvc/klm_prot.h>"},
-      {"include/rpcsvc/sm_inter.h", "<rpcsvc/sm_inter.h>"},
-      {"include/rpcsvc/nlm_prot.h", "<rpcsvc/nlm_prot.h>"},
-      {"include/rpcsvc/yp_prot.h", "<rpcsvc/yp_prot.h>"},
-      {"include/rpcsvc/ypclnt.h", "<rpcsvc/ypclnt.h>"},
-      {"include/rpcsvc/rstat.x", "<rpcsvc/rstat.x>"},
-      {"include/rpcsvc/rusers.h", "<rpcsvc/rusers.h>"},
-      {"include/rpcsvc/key_prot.x", "<rpcsvc/key_prot.x>"},
-      {"include/rpcsvc/sm_inter.x", "<rpcsvc/sm_inter.x>"},
-      {"include/rpcsvc/rquota.h", "<rpcsvc/rquota.h>"},
-      {"include/rpcsvc/nis.x", "<rpcsvc/nis.x>"},
-      {"include/rpcsvc/bootparam_prot.h", "<rpcsvc/bootparam_prot.h>"},
-      {"include/rpcsvc/mount.h", "<rpcsvc/mount.h>"},
-      {"include/rpcsvc/mount.x", "<rpcsvc/mount.x>"},
-      {"include/rpcsvc/nis_object.x", "<rpcsvc/nis_object.x>"},
-      {"include/rpcsvc/yppasswd.x", "<rpcsvc/yppasswd.x>"},
-      {"sys/acct.h", "<sys/acct.h>"},
-      {"sys/auxv.h", "<sys/auxv.h>"},
-      {"sys/cdefs.h", "<sys/cdefs.h>"},
-      {"sys/debugreg.h", "<sys/debugreg.h>"},
-      {"sys/dir.h", "<sys/dir.h>"},
-      {"sys/elf.h", "<sys/elf.h>"},
-      {"sys/epoll.h", "<sys/epoll.h>"},
-      {"sys/eventfd.h", "<sys/eventfd.h>"},
-      {"sys/fanotify.h", "<sys/fanotify.h>"},
-      {"sys/file.h", "<sys/file.h>"},
-      {"sys/fsuid.h", "<sys/fsuid.h>"},
-      {"sys/gmon.h", "<sys/gmon.h>"},
-      {"sys/gmon_out.h", "<sys/gmon_out.h>"},
-      {"sys/inotify.h", "<sys/inotify.h>"},
-      {"sys/io.h", "<sys/io.h>"},
-      {"sys/ioctl.h", "<sys/ioctl.h>"},
-      {"sys/ipc.h", "<sys/ipc.h>"},
-      {"sys/kd.h", "<sys/kd.h>"},
-      {"sys/kdaemon.h", "<sys/kdaemon.h>"},
-      {"sys/klog.h", "<sys/klog.h>"},
-      {"sys/mman.h", "<sys/mman.h>"},
-      {"sys/mount.h", "<sys/mount.h>"},
-      {"sys/msg.h", "<sys/msg.h>"},
-      {"sys/mtio.h", "<sys/mtio.h>"},
-      {"sys/param.h", "<sys/param.h>"},
-      {"sys/pci.h", "<sys/pci.h>"},
-      {"sys/perm.h", "<sys/perm.h>"},
-      {"sys/personality.h", "<sys/personality.h>"},
-      {"sys/poll.h", "<sys/poll.h>"},
-      {"sys/prctl.h", "<sys/prctl.h>"},
-      {"sys/procfs.h", "<sys/procfs.h>"},
-      {"sys/profil.h", "<sys/profil.h>"},
-      {"sys/ptrace.h", "<sys/ptrace.h>"},
-      {"sys/queue.h", "<sys/queue.h>"},
-      {"sys/quota.h", "<sys/quota.h>"},
-      {"sys/raw.h", "<sys/raw.h>"},
-      {"sys/reboot.h", "<sys/reboot.h>"},
-      {"sys/reg.h", "<sys/reg.h>"},
-      {"sys/resource.h", "<sys/resource.h>"},
-      {"sys/select.h", "<sys/select.h>"},
-      {"sys/sem.h", "<sys/sem.h>"},
-      {"sys/sendfile.h", "<sys/sendfile.h>"},
-      {"sys/shm.h", "<sys/shm.h>"},
-      {"sys/signalfd.h", "<sys/signalfd.h>"},
-      {"sys/socket.h", "<sys/socket.h>"},
-      {"sys/stat.h", "<sys/stat.h>"},
-      {"sys/statfs.h", "<sys/statfs.h>"},
-      {"sys/statvfs.h", "<sys/statvfs.h>"},
-      {"sys/swap.h", "<sys/swap.h>"},
-      {"sys/syscall.h", "<sys/syscall.h>"},
-      {"sys/sysctl.h", "<sys/sysctl.h>"},
-      {"sys/sysinfo.h", "<sys/sysinfo.h>"},
-      {"sys/syslog.h", "<sys/syslog.h>"},
-      {"sys/sysmacros.h", "<sys/sysmacros.h>"},
-      {"sys/termios.h", "<sys/termios.h>"},
-      {"sys/time.h", "<sys/select.h>"},
-      {"sys/timeb.h", "<sys/timeb.h>"},
-      {"sys/timerfd.h", "<sys/timerfd.h>"},
-      {"sys/times.h", "<sys/times.h>"},
-      {"sys/timex.h", "<sys/timex.h>"},
-      {"sys/ttychars.h", "<sys/ttychars.h>"},
-      {"sys/ttydefaults.h", "<sys/ttydefaults.h>"},
-      {"sys/types.h", "<sys/types.h>"},
-      {"sys/ucontext.h", "<sys/ucontext.h>"},
-      {"sys/uio.h", "<sys/uio.h>"},
-      {"sys/un.h", "<sys/un.h>"},
-      {"sys/user.h", "<sys/user.h>"},
-      {"sys/ustat.h", "<sys/ustat.h>"},
-      {"sys/utsname.h", "<sys/utsname.h>"},
-      {"sys/vlimit.h", "<sys/vlimit.h>"},
-      {"sys/vm86.h", "<sys/vm86.h>"},
-      {"sys/vtimes.h", "<sys/vtimes.h>"},
-      {"sys/wait.h", "<sys/wait.h>"},
-      {"sys/xattr.h", "<sys/xattr.h>"},
-      {"bits/epoll.h", "<sys/epoll.h>"},
-      {"bits/eventfd.h", "<sys/eventfd.h>"},
-      {"bits/inotify.h", "<sys/inotify.h>"},
-      {"bits/ipc.h", "<sys/ipc.h>"},
-      {"bits/ipctypes.h", "<sys/ipc.h>"},
-      {"bits/mman-linux.h", "<sys/mman.h>"},
-      {"bits/mman.h", "<sys/mman.h>"},
-      {"bits/msq.h", "<sys/msg.h>"},
-      {"bits/resource.h", "<sys/resource.h>"},
-      {"bits/sem.h", "<sys/sem.h>"},
-      {"bits/shm.h", "<sys/shm.h>"},
-      {"bits/signalfd.h", "<sys/signalfd.h>"},
-      {"bits/statfs.h", "<sys/statfs.h>"},
-      {"bits/statvfs.h", "<sys/statvfs.h>"},
-      {"bits/timerfd.h", "<sys/timerfd.h>"},
-      {"bits/utsname.h", "<sys/utsname.h>"},
-      {"bits/auxv.h", "<sys/auxv.h>"},
-      {"bits/byteswap-16.h", "<byteswap.h>"},
-      {"bits/byteswap.h", "<byteswap.h>"},
-      {"bits/confname.h", "<unistd.h>"},
-      {"bits/dirent.h", "<dirent.h>"},
-      {"bits/dlfcn.h", "<dlfcn.h>"},
-      {"bits/elfclass.h", "<link.h>"},
-      {"bits/endian.h", "<endian.h>"},
-      {"bits/environments.h", "<unistd.h>"},
-      {"bits/fcntl-linux.h", "<fcntl.h>"},
-      {"bits/fcntl.h", "<fcntl.h>"},
-      {"bits/in.h", "<netinet/in.h>"},
-      {"bits/ioctl-types.h", "<sys/ioctl.h>"},
-      {"bits/ioctls.h", "<sys/ioctl.h>"},
-      {"bits/link.h", "<link.h>"},
-      {"bits/mqueue.h", "<mqueue.h>"},
-      {"bits/netdb.h", "<netdb.h>"},
-      {"bits/param.h", "<sys/param.h>"},
-      {"bits/poll.h", "<sys/poll.h>"},
-      {"bits/posix_opt.h", "<bits/posix_opt.h>"},
-      {"bits/pthreadtypes.h", "<pthread.h>"},
-      {"bits/sched.h", "<sched.h>"},
-      {"bits/select.h", "<sys/select.h>"},
-      {"bits/semaphore.h", "<semaphore.h>"},
-      {"bits/sigthread.h", "<pthread.h>"},
-      {"bits/sockaddr.h", "<sys/socket.h>"},
-      {"bits/socket.h", "<sys/socket.h>"},
-      {"bits/socket_type.h", "<sys/socket.h>"},
-      {"bits/stab.def", "<stab.h>"},
-      {"bits/stat.h", "<sys/stat.h>"},
-      {"bits/stropts.h", "<stropts.h>"},
-      {"bits/syscall.h", "<sys/syscall.h>"},
-      {"bits/syslog-path.h", "<sys/syslog.h>"},
-      {"bits/termios.h", "<termios.h>"},
-      {"bits/types.h", "<sys/types.h>"},
-      {"bits/typesizes.h", "<sys/types.h>"},
-      {"bits/uio.h", "<sys/uio.h>"},
-      {"bits/ustat.h", "<sys/ustat.h>"},
-      {"bits/utmp.h", "<utmp.h>"},
-      {"bits/utmpx.h", "<utmpx.h>"},
-      {"bits/waitflags.h", "<sys/wait.h>"},
-      {"bits/waitstatus.h", "<sys/wait.h>"},
-      {"bits/xtitypes.h", "<stropts.h>"},
-  });
-  // Check MaxSuffixComponents constant is correct.
-  assert(llvm::all_of(SystemHeaderMap->keys(), [](llvm::StringRef Path) {
-    return std::distance(
-               llvm::sys::path::begin(Path, llvm::sys::path::Style::posix),
-               llvm::sys::path::end(Path)) <= MaxSuffixComponents;
-  }));
-  // ... and precise.
-  assert(llvm::find_if(SystemHeaderMap->keys(), [](llvm::StringRef Path) {
-           return std::distance(llvm::sys::path::begin(
-                                    Path, llvm::sys::path::Style::posix),
-                                llvm::sys::path::end(Path)) ==
-                  MaxSuffixComponents;
-         }) != SystemHeaderMap->keys().end());
-
-  // FIXME: Suffix mapping contains invalid entries for C, so only enable it for
-  // CPP.
-  if (Language.CPlusPlus)
-    StdSuffixHeaderMapping = SystemHeaderMap;
 }
 
 } // namespace clangd
diff --git a/clang-tools-extra/clangd/unittests/CanonicalIncludesTests.cpp b/clang-tools-extra/clangd/unittests/CanonicalIncludesTests.cpp
--- a/clang-tools-extra/clangd/unittests/CanonicalIncludesTests.cpp
+++ b/clang-tools-extra/clangd/unittests/CanonicalIncludesTests.cpp
@@ -21,10 +21,6 @@
   CI.addSystemHeadersMapping(Language);
   // Usual standard library symbols are mapped correctly.
   EXPECT_EQ("<stdio.h>", CI.mapHeader("path/stdio.h", "printf"));
-  // Suffix mapping isn't available for C, instead of mapping to `<cstdio> we
-  // just leave the header as-is.
-  EXPECT_EQ("include/stdio.h",
-            CI.mapHeader("include/stdio.h", "unknown_symbol"));
 }
 
 TEST(CanonicalIncludesTest, CXXStandardLibrary) {
@@ -37,14 +33,13 @@
   EXPECT_EQ("<vector>", CI.mapHeader("path/vector.h", "std::vector"));
   EXPECT_EQ("<cstdio>", CI.mapHeader("path/stdio.h", "std::printf"));
   // std::move is ambiguous, currently mapped only based on path
-  EXPECT_EQ("<utility>", CI.mapHeader("libstdc++/bits/move.h", "std::move"));
+  EXPECT_EQ("libstdc++/bits/move.h",
+            CI.mapHeader("libstdc++/bits/move.h", "std::move"));
   EXPECT_EQ("path/utility.h", CI.mapHeader("path/utility.h", "std::move"));
   // Unknown std symbols aren't mapped.
   EXPECT_EQ("foo/bar.h", CI.mapHeader("foo/bar.h", "std::notathing"));
   // iosfwd declares some symbols it doesn't own.
   EXPECT_EQ("<ostream>", CI.mapHeader("iosfwd", "std::ostream"));
-  // And (for now) we assume it owns the others.
-  EXPECT_EQ("<iosfwd>", CI.mapHeader("iosfwd", "std::notwathing"));
 }
 
 TEST(CanonicalIncludesTest, PathMapping) {
@@ -77,8 +72,6 @@
 
   // We added a mapping from some/path to <path>.
   ASSERT_EQ("<path>", CI.mapHeader("some/path", ""));
-  // We should have a path from 'bits/stl_vector.h' to '<vector>'.
-  ASSERT_EQ("<vector>", CI.mapHeader("bits/stl_vector.h", ""));
   // We should also have a symbol mapping from 'std::map' to '<map>'.
   ASSERT_EQ("<map>", CI.mapHeader("some/header.h", "std::map"));
 
diff --git a/clang-tools-extra/clangd/unittests/FileIndexTests.cpp b/clang-tools-extra/clangd/unittests/FileIndexTests.cpp
--- a/clang-tools-extra/clangd/unittests/FileIndexTests.cpp
+++ b/clang-tools-extra/clangd/unittests/FileIndexTests.cpp
@@ -226,10 +226,11 @@
 
 TEST(FileIndexTest, HasSystemHeaderMappingsInPreamble) {
   TestTU TU;
-  TU.HeaderCode = "class Foo{};";
-  TU.HeaderFilename = "algorithm";
+  // std::max is mapped back to <algorithm>
+  TU.HeaderCode = "namespace std { void max(); }";
+  TU.HeaderFilename = "ignored_header_name.h";
 
-  auto Symbols = runFuzzyFind(*TU.index(), "");
+  auto Symbols = runFuzzyFind(*TU.index(), "max");
   EXPECT_THAT(Symbols, ElementsAre(_));
   EXPECT_THAT(Symbols.begin()->IncludeHeaders.front().IncludeHeader,
               "<algorithm>");