diff --git a/Library/Formula/pixman.rb b/Library/Formula/pixman.rb
index 49b80a22f190..a302d4bae33c 100644
--- a/Library/Formula/pixman.rb
+++ b/Library/Formula/pixman.rb
@@ -7,7 +7,14 @@ class Pixman < Formula
 
   depends_on 'pkg-config' => :build
 
-  fails_with :llvm
+  fails_with :llvm do
+    build 2336
+    cause <<-EOS.undent
+      Building with llvm-gcc causes PDF rendering issues in Cairo.
+      https://trac.macports.org/ticket/30370
+      See Homebrew issues #6631, #7140, #7463, #7523.
+      EOS
+  end
 
   def options
     [["--universal", "Build a universal binary."]]