Index: llvm/cmake/config-ix.cmake
===================================================================
--- llvm/cmake/config-ix.cmake
+++ llvm/cmake/config-ix.cmake
@@ -43,7 +43,6 @@
 check_include_file(termios.h HAVE_TERMIOS_H)
 check_include_file(unistd.h HAVE_UNISTD_H)
 check_include_file(valgrind/valgrind.h HAVE_VALGRIND_VALGRIND_H)
-check_include_file(zlib.h HAVE_ZLIB_H)
 check_include_file(fenv.h HAVE_FENV_H)
 check_symbol_exists(FE_ALL_EXCEPT "fenv.h" HAVE_DECL_FE_ALL_EXCEPT)
 check_symbol_exists(FE_INEXACT "fenv.h" HAVE_DECL_FE_INEXACT)
@@ -105,17 +104,12 @@
 # Don't look for these libraries if we're using MSan, since uninstrumented third
 # party code may call MSan interceptors like strlen, leading to false positives.
 if(NOT LLVM_USE_SANITIZER MATCHES "Memory.*")
-  set(HAVE_LIBZ 0)
   if(LLVM_ENABLE_ZLIB)
-    foreach(library z zlib_static zlib)
-      string(TOUPPER ${library} library_suffix)
-      check_library_exists(${library} compress2 "" HAVE_LIBZ_${library_suffix})
-      if(HAVE_LIBZ_${library_suffix})
-        set(HAVE_LIBZ 1)
-        set(ZLIB_LIBRARIES "${library}")
-        break()
-      endif()
-    endforeach()
+    find_package(ZLIB)
+    if (ZLIB_FOUND)
+      set(HAVE_LIBZ TRUE)
+      include_directories(${ZLIB_INCLUDE_DIR})
+    endif()
   endif()
 
   # Don't look for these libraries on Windows.
@@ -481,13 +475,6 @@
   message(STATUS "Threads disabled.")
 endif()
 
-if (LLVM_ENABLE_ZLIB )
-  # Check if zlib is available in the system.
-  if ( NOT HAVE_ZLIB_H OR NOT HAVE_LIBZ )
-    set(LLVM_ENABLE_ZLIB 0)
-  endif()
-endif()
-
 if (LLVM_ENABLE_DOXYGEN)
   message(STATUS "Doxygen enabled.")
   find_package(Doxygen REQUIRED)
Index: llvm/include/llvm/Config/config.h.cmake
===================================================================
--- llvm/include/llvm/Config/config.h.cmake
+++ llvm/include/llvm/Config/config.h.cmake
@@ -223,9 +223,6 @@
 /* Define to 1 if you have the <valgrind/valgrind.h> header file. */
 #cmakedefine HAVE_VALGRIND_VALGRIND_H ${HAVE_VALGRIND_VALGRIND_H}
 
-/* Define to 1 if you have the <zlib.h> header file. */
-#cmakedefine HAVE_ZLIB_H ${HAVE_ZLIB_H}
-
 /* Have host's _alloca */
 #cmakedefine HAVE__ALLOCA ${HAVE__ALLOCA}
 
@@ -293,9 +290,6 @@
 /* Doesn't use `cmakedefine` because it is allowed to be empty. */
 #define LLVM_DEFAULT_TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}"
 
-/* Define if zlib compression is available */
-#cmakedefine01 LLVM_ENABLE_ZLIB
-
 /* Define if overriding target triple is enabled */
 #cmakedefine LLVM_TARGET_TRIPLE_ENV "${LLVM_TARGET_TRIPLE_ENV}"
 
Index: llvm/lib/Support/CMakeLists.txt
===================================================================
--- llvm/lib/Support/CMakeLists.txt
+++ llvm/lib/Support/CMakeLists.txt
@@ -1,5 +1,5 @@
 set(system_libs)
-if ( LLVM_ENABLE_ZLIB AND HAVE_LIBZ )
+if ( HAVE_LIBZ )
   set(system_libs ${system_libs} ${ZLIB_LIBRARIES})
 endif()
 if( MSVC OR MINGW )
Index: llvm/lib/Support/Compression.cpp
===================================================================
--- llvm/lib/Support/Compression.cpp
+++ llvm/lib/Support/Compression.cpp
@@ -18,13 +18,13 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
-#if LLVM_ENABLE_ZLIB == 1 && HAVE_ZLIB_H
+#if HAVE_LIBZ
 #include <zlib.h>
 #endif
 
 using namespace llvm;
 
-#if LLVM_ENABLE_ZLIB == 1 && HAVE_LIBZ
+#if HAVE_LIBZ
 static Error createError(StringRef Err) {
   return make_error<StringError>(Err, inconvertibleErrorCode());
 }
Index: llvm/unittests/Support/CompressionTest.cpp
===================================================================
--- llvm/unittests/Support/CompressionTest.cpp
+++ llvm/unittests/Support/CompressionTest.cpp
@@ -22,7 +22,7 @@
 
 namespace {
 
-#if LLVM_ENABLE_ZLIB == 1 && HAVE_LIBZ
+#if HAVE_LIBZ
 
 void TestZlibCompression(StringRef Input, zlib::CompressionLevel Level) {
   SmallString<32> Compressed;