diff --git a/Library/Homebrew/os/mac.rb b/Library/Homebrew/os/mac.rb
index bc384da308870..5074665fca5c5 100644
--- a/Library/Homebrew/os/mac.rb
+++ b/Library/Homebrew/os/mac.rb
@@ -207,6 +207,8 @@ def preferred_arch
       "8.3"   => { clang: "8.1", clang_build: 802 },
       "8.3.1" => { clang: "8.1", clang_build: 802 },
       "8.3.2" => { clang: "8.1", clang_build: 802 },
+      "8.3.3" => { clang: "8.1", clang_build: 802 },
+      "9.0"   => { clang: "9.0", clang_build: 900 },
     }.freeze
 
     def compilers_standard?
diff --git a/Library/Homebrew/os/mac/xcode.rb b/Library/Homebrew/os/mac/xcode.rb
index 9ed95d3f2d659..20ce6b74fc615 100644
--- a/Library/Homebrew/os/mac/xcode.rb
+++ b/Library/Homebrew/os/mac/xcode.rb
@@ -17,17 +17,19 @@ def latest_version
         when "10.9"  then "6.2"
         when "10.10" then "7.2.1"
         when "10.11" then "8.2.1"
-        when "10.12" then "8.3.2"
+        when "10.12" then "8.3.3"
+        when "10.13" then "9.0"
         else
           raise "macOS '#{MacOS.version}' is invalid" unless OS::Mac.prerelease?
 
           # Default to newest known version of Xcode for unreleased macOS versions.
-          "8.3.2"
+          "9.0"
         end
       end
 
       def minimum_version
         case MacOS.version
+        when "10.13" then "9.0"
         when "10.12" then "8.0"
         else "2.0"
         end
@@ -152,7 +154,8 @@ def uncached_version
         when 73      then "7.3"
         when 80      then "8.0"
         when 81      then "8.3"
-        else "8.3"
+        when 90      then "9.0"
+        else "9.0"
         end
       end
 
diff --git a/docs/Xcode.md b/docs/Xcode.md
index 7c2cca5c8f3c5..21ad66f95dc10 100644
--- a/docs/Xcode.md
+++ b/docs/Xcode.md
@@ -12,7 +12,7 @@ Tools available for your platform:
 | 10.9  | 6.2   | 6.2                |
 | 10.10 | 7.2.1 | 7.2                |
 | 10.11 | 8.2.1 | 8.2                |
-| 10.12 | 8.3.2 | 8.3                |
+| 10.12 | 8.3.3 | 8.3                |
 
 ## Compiler version database
 
@@ -72,6 +72,7 @@ Tools available for your platform:
 | 8.3   | —       | —       | —            | —          | 8.1 (802.0.38)  | —          |
 | 8.3.1 | —       | —       | —            | —          | 8.1 (802.0.41)  | —          |
 | 8.3.2 | —       | —       | —            | —          | 8.1 (802.0.42)  | —          |
+| 8.3.3 | —       | —       | —            | —          | 8.1 (802.0.42)  | —          |
 
 ## References to Xcode and compiler versions in code
 When a new Xcode release is made, the following things need to be