diff --git a/contrib/llvm-project/llvm/lib/Support/Threading.cpp b/contrib/llvm-project/llvm/lib/Support/Threading.cpp
index 04a1a9e19428..3ac3695fa9ed 100644
--- a/contrib/llvm-project/llvm/lib/Support/Threading.cpp
+++ b/contrib/llvm-project/llvm/lib/Support/Threading.cpp
@@ -1,116 +1,127 @@
 //===-- llvm/Support/Threading.cpp- Control multithreading mode --*- C++ -*-==//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines helper functions for running LLVM in a multi-threaded
 // environment.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/Threading.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/Config/config.h"
 #include "llvm/Support/Host.h"
 
 #include <cassert>
 #include <errno.h>
 #include <stdlib.h>
 #include <string.h>
 
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//
 //=== WARNING: Implementation here must contain only TRULY operating system
 //===          independent code.
 //===----------------------------------------------------------------------===//
 
 bool llvm::llvm_is_multithreaded() {
 #if LLVM_ENABLE_THREADS != 0
   return true;
 #else
   return false;
 #endif
 }
 
 #if LLVM_ENABLE_THREADS == 0 ||                                                \
     (!defined(_WIN32) && !defined(HAVE_PTHREAD_H))
 uint64_t llvm::get_threadid() { return 0; }
 
 uint32_t llvm::get_max_thread_name_length() { return 0; }
 
 void llvm::set_thread_name(const Twine &Name) {}
 
 void llvm::get_thread_name(SmallVectorImpl<char> &Name) { Name.clear(); }
 
 llvm::BitVector llvm::get_thread_affinity_mask() { return {}; }
 
 unsigned llvm::ThreadPoolStrategy::compute_thread_count() const {
   // When threads are disabled, ensure clients will loop at least once.
   return 1;
 }
 
 #else
 
 int computeHostNumHardwareThreads();
 
 unsigned llvm::ThreadPoolStrategy::compute_thread_count() const {
   int MaxThreadCount = UseHyperThreads ? computeHostNumHardwareThreads()
                                        : sys::getHostNumPhysicalCores();
   if (MaxThreadCount <= 0)
     MaxThreadCount = 1;
-  if (ThreadsRequested == 0)
-    return MaxThreadCount;
+  // Damage control threading.
+  //
+  // There are no heuristics to figure out how many threads makes sense to spawn,
+  // all while rolling with all available hw threads starts being detrimental to
+  // performance really early.
+  //
+  // Work around by putting a hard cap unless the user explicitly requested a certain amount.
+  //
+  // See https://discourse.llvm.org/t/avoidable-overhead-from-threading-by-default/69160
+  // for more details.
+  if (ThreadsRequested == 0) {
+    return std::min(MaxThreadCount, 4);
+  }
   if (!Limit)
     return ThreadsRequested;
   return std::min((unsigned)MaxThreadCount, ThreadsRequested);
 }
 
 // Include the platform-specific parts of this class.
 #ifdef LLVM_ON_UNIX
 #include "Unix/Threading.inc"
 #endif
 #ifdef _WIN32
 #include "Windows/Threading.inc"
 #endif
 
 // Must be included after Threading.inc to provide definition for llvm::thread
 // because FreeBSD's condvar.h (included by user.h) misuses the "thread"
 // keyword.
 #include "llvm/Support/thread.h"
 
 #if defined(__APPLE__)
   // Darwin's default stack size for threads except the main one is only 512KB,
   // which is not enough for some/many normal LLVM compilations. This implements
   // the same interface as std::thread but requests the same stack size as the
   // main thread (8MB) before creation.
 const llvm::Optional<unsigned> llvm::thread::DefaultStackSize = 8 * 1024 * 1024;
 #else
 const llvm::Optional<unsigned> llvm::thread::DefaultStackSize = None;
 #endif
 
 
 #endif
 
 Optional<ThreadPoolStrategy>
 llvm::get_threadpool_strategy(StringRef Num, ThreadPoolStrategy Default) {
   if (Num == "all")
     return llvm::hardware_concurrency();
   if (Num.empty())
     return Default;
   unsigned V;
   if (Num.getAsInteger(10, V))
     return None; // malformed 'Num' value
   if (V == 0)
     return Default;
 
   // Do not take the Default into account. This effectively disables
   // heavyweight_hardware_concurrency() if the user asks for any number of
   // threads on the cmd-line.
   ThreadPoolStrategy S = llvm::hardware_concurrency();
   S.ThreadsRequested = V;
   return S;
 }