diff --git a/Make.config b/Make.config
index fc62d06533..556c9a5caa 100644
--- a/Make.config
+++ b/Make.config
@@ -57,9 +57,9 @@ XCODE_URL=http://xamarin-storage/bot-provisioning/Xcode_9_GM_seed.xip
 XCODE_DEVELOPER_ROOT=/Applications/Xcode9-GM.app/Contents/Developer
 
 # Minimum Mono version
-MIN_MONO_VERSION=5.6.0.0
-MAX_MONO_VERSION=5.6.99
-MIN_MONO_URL=https://bosstoragemirror.azureedge.net/wrench/mono-2017-08/94/9417be0f1183e100e7c88953d5944e1a59d5ef5f/MonoFramework-MDK-5.6.0.0.macos10.xamarin.universal.pkg
+MIN_MONO_VERSION=5.8.0.0
+MAX_MONO_VERSION=5.8.99
+MIN_MONO_URL=https://bosstoragemirror.azureedge.net/wrench/mono-2017-10/8a/8a2a0628624e9a7456b0ec1831dd68998750df62/MonoFramework-MDK-5.8.0.0.macos10.xamarin.universal.pkg
 
 # Minimum Visual Studio version
 MIN_VISUAL_STUDIO_URL=https://bosstoragemirror.blob.core.windows.net/wrench/monodevelop-lion-dogfood-vNext/8f/8f1c13cb983138ee63bd53e09908ea5e737988cd/VisualStudioForMac-Preview-7.0.0.2728.dmg
diff --git a/external/llvm b/external/llvm
index 975e3a6903..21492ec92e 160000
--- a/external/llvm
+++ b/external/llvm
@@ -1 +1 @@
-Subproject commit 975e3a6903003d7dba1b01f8a3c4a42a55049842
+Subproject commit 21492ec92e255a43bc6b687468f1eb18a635d94e
diff --git a/external/mono b/external/mono
index 48e94bd5f6..8a2a062862 160000
--- a/external/mono
+++ b/external/mono
@@ -1 +1 @@
-Subproject commit 48e94bd5f61c5e960d1cf6cd8066106881331451
+Subproject commit 8a2a0628624e9a7456b0ec1831dd68998750df62