diff --git a/pkgs/build-support/bintools-wrapper/default.nix b/pkgs/build-support/bintools-wrapper/default.nix
index 9e31ca6a8a21..786f0f9c5983 100644
--- a/pkgs/build-support/bintools-wrapper/default.nix
+++ b/pkgs/build-support/bintools-wrapper/default.nix
@@ -132,15 +132,15 @@ stdenv.mkDerivation {
       ldPath="${bintools_bin}/bin"
     ''
 
+    # Solaris needs an additional ld wrapper.
     + optionalString (targetPlatform.isSunOS && nativePrefix != "") ''
-      # Solaris needs an additional ld wrapper.
       ldPath="${nativePrefix}/bin"
       exec="$ldPath/${targetPrefix}ld"
       wrap ld-solaris ${./ld-solaris-wrapper.sh}
     '')
 
+    # Create a symlink to as (the assembler).
     + ''
-      # Create a symlink to as (the assembler).
       if [ -e $ldPath/${targetPrefix}as ]; then
         ln -s $ldPath/${targetPrefix}as $out/bin/${targetPrefix}as
       fi
@@ -200,26 +200,29 @@ stdenv.mkDerivation {
   ];
 
   postFixup =
+    ##
+    ## General libc support
+    ##
     optionalString (libc != null) (''
-      ##
-      ## General libc support
-      ##
-
-      echo "-L${libc_lib}${libc.libdir or "/lib"}" > $out/nix-support/libc-ldflags
+      touch "$out/nix-support/libc-ldflags"
+      echo "-L${libc_lib}${libc.libdir or "/lib"}" >> $out/nix-support/libc-ldflags
 
       echo "${libc_lib}" > $out/nix-support/orig-libc
       echo "${libc_dev}" > $out/nix-support/orig-libc-dev
+    ''
 
-      ##
-      ## Dynamic linker support
-      ##
-
+    ##
+    ## Dynamic linker support
+    ##
+    + ''
       if [[ -z ''${dynamicLinker+x} ]]; then
         echo "Don't know the name of the dynamic linker for platform '${targetPlatform.config}', so guessing instead." >&2
         local dynamicLinker="${libc_lib}/lib/ld*.so.?"
       fi
+    ''
 
-      # Expand globs to fill array of options
+    # Expand globs to fill array of options
+    + ''
       dynamicLinker=($dynamicLinker)
 
       case ''${#dynamicLinker[@]} in
@@ -228,58 +231,56 @@ stdenv.mkDerivation {
         *) echo "Multiple dynamic linkers found for platform '${targetPlatform.config}'." >&2;;
       esac
 
-      if [ -n "''${dynamicLinker:-}" ]; then
+      if [ -n "''${dynamicLinker-}" ]; then
         echo $dynamicLinker > $out/nix-support/dynamic-linker
 
     '' + (if targetPlatform.isDarwin then ''
         printf "export LD_DYLD_PATH=%q\n" "$dynamicLinker" >> $out/nix-support/setup-hook
-    '' else ''
+      '' else ''
         if [ -e ${libc_lib}/lib/32/ld-linux.so.2 ]; then
           echo ${libc_lib}/lib/32/ld-linux.so.2 > $out/nix-support/dynamic-linker-m32
         fi
-
-        local ldflagsBefore=(-dynamic-linker "$dynamicLinker")
-    '') + ''
-      fi
-
+      ''
       # The dynamic linker is passed in `ldflagsBefore' to allow
       # explicit overrides of the dynamic linker by callers to ld
       # (the *last* value counts, so ours should come first).
-      printWords "''${ldflagsBefore[@]}" > $out/nix-support/libc-ldflags-before
+      + ''
+        echo -dynamic-linker "$dynamicLinker" >> $out/nix-support/libc-ldflags-before
+    '') + ''
+      fi
     '')
 
+    # Ensure consistent LC_VERSION_MIN_MACOSX and remove LC_UUID.
     + optionalString stdenv.targetPlatform.isMacOS ''
-      # Ensure consistent LC_VERSION_MIN_MACOSX and remove LC_UUID.
       echo "-macosx_version_min 10.12 -sdk_version 10.12 -no_uuid" >> $out/nix-support/libc-ldflags-before
     ''
 
-    + optionalString (!nativeTools) ''
-      ##
-      ## User env support
-      ##
+    ##
+    ## User env support
+    ##
 
-      # Propagate the underling unwrapped bintools so that if you
-      # install the wrapper, you get tools like objdump (same for any
-      # binaries of libc).
+    # Propagate the underling unwrapped bintools so that if you
+    # install the wrapper, you get tools like objdump (same for any
+    # binaries of libc).
+    + optionalString (!nativeTools) ''
       printWords ${bintools_bin} ${if libc == null then "" else libc_bin} > $out/nix-support/propagated-user-env-packages
     ''
 
+    ##
+    ## Man page and info support
+    ##
     + optionalString propagateDoc (''
-      ##
-      ## Man page and info support
-      ##
-
       ln -s ${bintools.man} $man
     '' + optionalString (bintools ? info) ''
       ln -s ${bintools.info} $info
     '')
 
-    + ''
-      ##
-      ## Hardening support
-      ##
+    ##
+    ## Hardening support
+    ##
 
-      # some linkers on some platforms don't support specific -z flags
+    # some linkers on some platforms don't support specific -z flags
+    + ''
       export hardening_unsupported_flags=""
       if [[ "$($ldPath/${targetPrefix}ld -z now 2>&1 || true)" =~ un(recognized|known)\ option ]]; then
         hardening_unsupported_flags+=" bindnow"
@@ -304,15 +305,18 @@ stdenv.mkDerivation {
     ''
 
     + ''
+      for flags in "$out/nix-support"/*flags*; do
+        substituteInPlace "$flags" --replace $'\n' ' '
+      done
+
       substituteAll ${./add-flags.sh} $out/nix-support/add-flags.sh
       substituteAll ${./add-hardening.sh} $out/nix-support/add-hardening.sh
       substituteAll ${../wrapper-common/utils.bash} $out/nix-support/utils.bash
-
-      ##
-      ## Extra custom steps
-      ##
     ''
 
+    ##
+    ## Extra custom steps
+    ##
     + extraBuildCommands;
 
   inherit dynamicLinker expand-response-params;
diff --git a/pkgs/build-support/cc-wrapper/default.nix b/pkgs/build-support/cc-wrapper/default.nix
index e23d1c6dd4e6..1fef3c459086 100644
--- a/pkgs/build-support/cc-wrapper/default.nix
+++ b/pkgs/build-support/cc-wrapper/default.nix
@@ -154,16 +154,18 @@ stdenv.mkDerivation {
       ccPath="${cc}/bin"
     '')
 
+    # Create symlinks to everything in the bintools wrapper.
     + ''
-      # Create symlinks to everything in the bintools wrapper.
       for bbin in $bintools/bin/*; do
         mkdir -p "$out/bin"
         ln -s "$bbin" "$out/bin/$(basename $bbin)"
       done
+    ''
 
-      # We export environment variables pointing to the wrapped nonstandard
-      # cmds, lest some lousy configure script use those to guess compiler
-      # version.
+    # We export environment variables pointing to the wrapped nonstandard
+    # cmds, lest some lousy configure script use those to guess compiler
+    # version.
+    + ''
       export named_cc=${targetPrefix}cc
       export named_cxx=${targetPrefix}c++
 
@@ -228,12 +230,19 @@ stdenv.mkDerivation {
   ];
 
   postFixup =
+    # Ensure flags files exists, as some other programs cat them. (That these
+    # are considered an exposed interface is a bit dubious, but fine for now.)
     ''
-      # Backwards compatability for packages expecting this file, e.g. with
-      # `$NIX_CC/nix-support/dynamic-linker`.
-      #
-      # TODO(@Ericson2314): Remove this after stable release and force
-      # everyone to refer to bintools-wrapper directly.
+      touch "$out/nix-support/cc-cflags"
+      touch "$out/nix-support/cc-ldflags"
+    ''
+
+    # Backwards compatability for packages expecting this file, e.g. with
+    # `$NIX_CC/nix-support/dynamic-linker`.
+    #
+    # TODO(@Ericson2314): Remove this after stable release and force
+    # everyone to refer to bintools-wrapper directly.
+    + ''
       if [[ -f "$bintools/nix-support/dynamic-linker" ]]; then
         ln -s "$bintools/nix-support/dynamic-linker" "$out/nix-support"
       fi
@@ -242,40 +251,42 @@ stdenv.mkDerivation {
       fi
     ''
 
+    ##
+    ## General Clang support
+    ##
     + optionalString isClang ''
-      ##
-      ## General Clang support
-      ##
 
       echo "-target ${targetPlatform.config}" >> $out/nix-support/cc-cflags
     ''
 
+    ##
+    ## GCC libs for non-GCC support
+    ##
     + optionalString (isClang && libcxx == null && cc ? gcc) ''
-      ##
-      ## GCC libs for non-GCC support
-      ##
 
       echo "-B${cc.gcc}/lib/gcc/${targetPlatform.config}/${cc.gcc.version}" >> $out/nix-support/cc-cflags
       echo "-L${cc.gcc}/lib/gcc/${targetPlatform.config}/${cc.gcc.version}" >> $out/nix-support/cc-ldflags
       echo "-L${cc.gcc.lib}/${targetPlatform.config}/lib" >> $out/nix-support/cc-ldflags
     ''
 
-    + optionalString (libc != null) (''
-      ##
-      ## General libc support
-      ##
+    ##
+    ## General libc support
+    ##
 
-      # The "-B${libc_lib}/lib/" flag is a quick hack to force gcc to link
-      # against the crt1.o from our own glibc, rather than the one in
-      # /usr/lib.  (This is only an issue when using an `impure'
-      # compiler/linker, i.e., one that searches /usr/lib and so on.)
-      #
-      # Unfortunately, setting -B appears to override the default search
-      # path. Thus, the gcc-specific "../includes-fixed" directory is
-      # now longer searched and glibc's <limits.h> header fails to
-      # compile, because it uses "#include_next <limits.h>" to find the
-      # limits.h file in ../includes-fixed. To remedy the problem,
-      # another -idirafter is necessary to add that directory again.
+    # The "-B${libc_lib}/lib/" flag is a quick hack to force gcc to link
+    # against the crt1.o from our own glibc, rather than the one in
+    # /usr/lib.  (This is only an issue when using an `impure'
+    # compiler/linker, i.e., one that searches /usr/lib and so on.)
+    #
+    # Unfortunately, setting -B appears to override the default search
+    # path. Thus, the gcc-specific "../includes-fixed" directory is
+    # now longer searched and glibc's <limits.h> header fails to
+    # compile, because it uses "#include_next <limits.h>" to find the
+    # limits.h file in ../includes-fixed. To remedy the problem,
+    # another -idirafter is necessary to add that directory again.
+    + optionalString (libc != null) (''
+      touch "$out/nix-support/libc-cflags"
+      touch "$out/nix-support/libc-ldflags"
       echo "-B${libc_lib}${libc.libdir or "/lib/"}" >> $out/nix-support/libc-cflags
     '' + optionalString (!(cc.langD or false)) ''
       echo "-idirafter ${libc_dev}${libc.incdir or "/include"}" >> $out/nix-support/libc-cflags
@@ -289,13 +300,16 @@ stdenv.mkDerivation {
       echo "${libc_dev}" > $out/nix-support/orig-libc-dev
     '')
 
-    + ''
-      ##
-      ## General libc++ support
-      ##
+    ##
+    ## General libc++ support
+    ##
 
-    ''
-    + optionalString (libcxx == null && cc ? gcc) ''
+    # We have a libc++ directly, we have one via "smuggled" GCC, or we have one
+    # bundled with the C compiler because it is GCC
+    + optionalString (libcxx != null || cc.gcc.langCC or false || (isGNU && cc.langCC or false)) ''
+      touch "$out/nix-support/libcxx-cxxflags"
+      touch "$out/nix-support/libcxx-ldflags"
+    '' + optionalString (libcxx == null && cc ? gcc) ''
       for dir in ${cc.gcc}/include/c++/*; do
         echo "-isystem $dir" >> $out/nix-support/libcxx-cxxflags
       done
@@ -310,15 +324,15 @@ stdenv.mkDerivation {
       echo "-lc++abi" >> $out/nix-support/libcxx-ldflags
     '')
 
-    + optionalString (!nativeTools) ''
-      ##
-      ## Initial CFLAGS
-      ##
+    ##
+    ## Initial CFLAGS
+    ##
 
-      # GCC shows ${cc_solib}/lib in `gcc -print-search-dirs', but not
-      # ${cc_solib}/lib64 (even though it does actually search there...)..
-      # This confuses libtool.  So add it to the compiler tool search
-      # path explicitly.
+    # GCC shows ${cc_solib}/lib in `gcc -print-search-dirs', but not
+    # ${cc_solib}/lib64 (even though it does actually search there...)..
+    # This confuses libtool.  So add it to the compiler tool search
+    # path explicitly.
+    + optionalString (!nativeTools) ''
       if [ -e "${cc_solib}/lib64" -a ! -L "${cc_solib}/lib64" ]; then
         ccLDFlags+=" -L${cc_solib}/lib64"
         ccCFlags+=" -B${cc_solib}/lib64"
@@ -327,32 +341,34 @@ stdenv.mkDerivation {
       ccCFlags+=" -B${cc_solib}/lib"
 
     '' + optionalString cc.langAda or false ''
+      touch "$out/nix-support/gnat-cflags"
+      touch "$out/nix-support/gnat-ldflags"
       basePath=$(echo $cc/lib/*/*/*)
       ccCFlags+=" -B$basePath -I$basePath/adainclude"
       gnatCFlags="-I$basePath/adainclude -I$basePath/adalib"
 
-      echo "$gnatCFlags" > $out/nix-support/gnat-cflags
+      echo "$gnatCFlags" >> $out/nix-support/gnat-cflags
     '' + ''
-      echo "$ccLDFlags" > $out/nix-support/cc-ldflags
-      echo "$ccCFlags" > $out/nix-support/cc-cflags
+      echo "$ccLDFlags" >> $out/nix-support/cc-ldflags
+      echo "$ccCFlags" >> $out/nix-support/cc-cflags
     '' + optionalString (targetPlatform.isDarwin && (libcxx != null) && (cc.isClang or false)) ''
       echo " -L${libcxx}/lib" >> $out/nix-support/cc-ldflags
-    '' + optionalString propagateDoc ''
-      ##
-      ## Man page and info support
-      ##
+    ''
 
+    ##
+    ## Man page and info support
+    ##
+    + optionalString propagateDoc ''
       ln -s ${cc.man} $man
       ln -s ${cc.info} $info
     '' + optionalString (cc.langD or false) ''
       echo "-B${zlib}${zlib.libdir or "/lib/"}" >> $out/nix-support/libc-cflags
     ''
 
+    ##
+    ## Hardening support
+    ##
     + ''
-      ##
-      ## Hardening support
-      ##
-
       export hardening_unsupported_flags="${builtins.concatStringsSep " " (cc.hardeningUnsupportedFlags or [])}"
     ''
 
@@ -420,19 +436,18 @@ stdenv.mkDerivation {
     # There are a few tools (to name one libstdcxx5) which do not work
     # well with multi line flags, so make the flags single line again
     + ''
-      for flags in "$out/nix-support"/*flags; do
+      for flags in "$out/nix-support"/*flags*; do
         substituteInPlace "$flags" --replace $'\n' ' '
       done
 
       substituteAll ${./add-flags.sh} $out/nix-support/add-flags.sh
       substituteAll ${./add-hardening.sh} $out/nix-support/add-hardening.sh
       substituteAll ${../wrapper-common/utils.bash} $out/nix-support/utils.bash
-
-      ##
-      ## Extra custom steps
-      ##
     ''
 
+    ##
+    ## Extra custom steps
+    ##
     + extraBuildCommands;
 
   inherit expand-response-params;