diff --git a/pkgs/development/interpreters/python/cpython/2.7/default.nix b/pkgs/development/interpreters/python/cpython/2.7/default.nix
index db86b67835e3..62aae7b22129 100644
--- a/pkgs/development/interpreters/python/cpython/2.7/default.nix
+++ b/pkgs/development/interpreters/python/cpython/2.7/default.nix
@@ -23,6 +23,7 @@
 , sha256
 , passthruFun
 , static ? false
+, enableOptimizations ? (!stdenv.isDarwin)
 }:
 
 assert x11Support -> tcl != null
@@ -138,8 +139,9 @@ let
         --replace 'os.popen(comm)' 'os.popen("${coreutils}/bin/nproc")'
     '';
 
-  configureFlags = [
+  configureFlags = optionals enableOptimizations [
     "--enable-optimizations"
+  ] ++ [
     "--enable-shared"
     "--with-threads"
     "--enable-unicode=ucs${toString ucsEncoding}"
diff --git a/pkgs/development/interpreters/python/cpython/default.nix b/pkgs/development/interpreters/python/cpython/default.nix
index ee77185cde65..694f661a9669 100644
--- a/pkgs/development/interpreters/python/cpython/default.nix
+++ b/pkgs/development/interpreters/python/cpython/default.nix
@@ -31,7 +31,9 @@
 , stripBytecode ? false
 , includeSiteCustomize ? true
 , static ? false
-, enableOptimizations ? true
+# Not using optimizations on Darwin
+# configure: error: llvm-profdata is required for a --enable-optimizations build but could not be found.
+, enableOptimizations ? (!stdenv.isDarwin)
 }:
 
 assert x11Support -> tcl != null
@@ -54,8 +56,9 @@ let
 
   version = with sourceVersion; "${major}.${minor}.${patch}${suffix}";
 
-  nativeBuildInputs = [
+  nativeBuildInputs = optionals (!stdenv.isDarwin) [
     autoreconfHook
+  ] ++ [
     nukeReferences
   ] ++ optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
     buildPackages.stdenv.cc