diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -36,6 +36,10 @@
   if( FUCHSIA )
     set(system_libs ${system_libs} zircon)
   endif()
+  if ( HAIKU )
+    add_definitions(-D_BSD_SOURCE)
+    set(system_libs ${system_libs} bsd)
+  endif()
 endif( MSVC OR MINGW )
 
 # Delay load shell32.dll if possible to speed up process startup.
diff --git a/llvm/lib/Support/Unix/Program.inc b/llvm/lib/Support/Unix/Program.inc
--- a/llvm/lib/Support/Unix/Program.inc
+++ b/llvm/lib/Support/Unix/Program.inc
@@ -452,8 +452,12 @@
   if (ProcStat) {
     std::chrono::microseconds UserT = toDuration(Info.ru_utime);
     std::chrono::microseconds KernelT = toDuration(Info.ru_stime);
+#ifndef __HAIKU__
     uint64_t PeakMemory = static_cast<uint64_t>(Info.ru_maxrss);
     *ProcStat = ProcessStatistics{UserT + KernelT, UserT, PeakMemory};
+#else
+    *ProcStat = ProcessStatistics{UserT + KernelT, UserT, 0};
+#endif
   }
 
   // Return the proper exit status. Detect error conditions