Index: llvm/include/llvm/Support/Threading.h
===================================================================
--- llvm/include/llvm/Support/Threading.h
+++ llvm/include/llvm/Support/Threading.h
@@ -15,6 +15,8 @@
 #ifndef LLVM_SUPPORT_THREADING_H
 #define LLVM_SUPPORT_THREADING_H
 
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
 #include "llvm/Config/llvm-config.h" // for LLVM_ON_UNIX
 #include "llvm/Support/Compiler.h"
 #include <ciso646> // So we can check the C++ standard lib macros.
@@ -127,6 +129,9 @@
   /// thread::hardware_concurrency().
   /// Returns 1 when LLVM is configured with LLVM_ENABLE_THREADS=OFF
   unsigned heavyweight_hardware_concurrency();
+
+  void set_thread_name(StringRef Name);
+  void get_thread_name(SmallVectorImpl<char> &Name);
 }
 
 #endif
Index: llvm/lib/Support/Threading.cpp
===================================================================
--- llvm/lib/Support/Threading.cpp
+++ llvm/lib/Support/Threading.cpp
@@ -13,12 +13,19 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/Threading.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/Config/config.h"
 #include "llvm/Support/Atomic.h"
 #include "llvm/Support/Host.h"
+#include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Mutex.h"
 #include "llvm/Support/thread.h"
+
 #include <cassert>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
 
 using namespace llvm;
 
@@ -33,6 +40,17 @@
 #if LLVM_ENABLE_THREADS != 0 && defined(HAVE_PTHREAD_H)
 #include <pthread.h>
 
+#if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+
+#include <sys/sysctl.h>
+#include <sys/user.h>
+
+#if defined(__FreeBSD__)
+#include <pthread_np.h>
+#endif
+
+#endif
+
 struct ThreadInfo {
   void (*UserFn)(void *);
   void *UserData;
@@ -127,3 +145,116 @@
     return thread::hardware_concurrency();
   return NumPhysical;
 }
+
+#if LLVM_ENABLE_THREADS == 0
+void llvm::get_thread_name(SmallVectorImpl<char> &) {}
+
+void llvm::set_thread_name(StringRef) {}
+
+#else
+void llvm::set_thread_name(StringRef Name) {
+  // Make sure the input is null terminated.
+  std::string NameStr(Name);
+#if defined(__linux__)
+#if (defined(__GLIBC__) && defined(_GNU_SOURCE)) || defined(__ANDROID__)
+  ::pthread_setname_np(::pthread_self(), NameStr.c_str());
+#endif
+#elif defined(__FreeBSD__)
+  ::pthread_set_name_np(::pthread_self(), NameStr.c_str());
+#elif defined(__NetBSD__)
+  ::pthread_setname_np(::pthread_self(), "%s",
+                       const_cast<char *>(NameStr.c_str()));
+#elif defined(__APPLE__)
+  ::pthread_setname_np(NameStr.c_str());
+#elif defined(_MSC_VER)
+  constexpr DWORD MS_VC_EXCEPTION = 0x406D1388;
+
+#pragma pack(push, 8)
+  struct THREADNAME_INFO {
+    DWORD dwType;     // Must be 0x1000.
+    LPCSTR szName;    // Pointer to thread name
+    DWORD dwThreadId; // Thread ID (-1 == current thread)
+    DWORD dwFlags;    // Reserved.  Do not use.
+  };
+#pragma pack(pop)
+
+  THREADNAME_INFO info;
+  info.dwType = 0x1000;
+  info.szName = NameStr.c_str();
+  info.dwThreadId = ::GetCurrentThreadId();
+  info.dwFlags = 0;
+
+  __try {
+    ::RaiseException(MS_VC_EXCEPTION, 0, sizeof(info) / sizeof(ULONG_PTR),
+                     (ULONG_PTR *)&info);
+  } __except (EXCEPTION_EXECUTE_HANDLER) {
+  }
+#endif
+}
+
+void llvm::get_thread_name(SmallVectorImpl<char> &Name) {
+  Name.clear();
+
+#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+#if defined(__FreeBSD_kernel__)
+  int pid = ::pthread_self();
+#else
+  int pid = ::getpid();
+#endif
+
+  int tid = ::pthread_getthreadid_np();
+
+  struct kinfo_proc *kp = nullptr, *nkp;
+  size_t len = 0;
+  int error;
+  int ctl[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PID | KERN_PROC_INC_THREAD,
+                (int)pid};
+
+  while (1) {
+    error = sysctl(ctl, 4, kp, &len, nullptr, 0);
+    if (kp == nullptr || (error != 0 && errno == ENOMEM)) {
+      // Add extra space in case threads are added before next call.
+      len += sizeof(*kp) + len / 10;
+      nkp = (struct kinfo_proc *)realloc(kp, len);
+      if (nkp == nullptr) {
+        free(kp);
+        return;
+      }
+      kp = nkp;
+      continue;
+    }
+    if (error != 0)
+      len = 0;
+    break;
+  }
+
+  for (size_t i = 0; i < len / sizeof(*kp); i++) {
+    if (kp[i].ki_tid == (lwpid_t)tid) {
+      Name.append(kp[i].ki_tdname, kp[i].ki_tdname + strlen(kp[i].ki_tdname));
+      break;
+    }
+  }
+  free(kp);
+  return;
+#elif defined(__NetBSD__)
+  char buf[PTHREAD_MAX_NAMELEN_NP];
+  ::pthread_getname_np(::pthread_self(), buf, PTHREAD_MAX_NAMELEN_NP);
+
+  Name.append(buf, buf + strlen(buf));
+#elif defined(__linux__)
+  // Read /proc/$TID/comm file.
+  SmallString<64> Path;
+  raw_svector_ostream Stream(Path);
+  Stream << "/proc/" << static_cast<uint64_t>(::pthread_self()) << "/comm";
+
+  auto Contents = MemoryBuffer::getFileAsStream(Path);
+  if (!Contents)
+    return;
+
+  StringRef CommData = (*Contents)->getBuffer();
+  StringRef Result = CommData.split('\n').first;
+
+  Name.append(Result.begin(), Result.end());
+#endif
+}
+#endif