diff --git a/.appveyor.yml b/.appveyor.yml
index 203aceea0e..db414739f6 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -10,8 +10,8 @@ branches:
 environment:
   matrix:
   - llvm: 3.9.1
-  - llvm: 4.0.1
   - llvm: 5.0.1
+  - llvm: 6.0.0
 
 configuration:
   - release
diff --git a/.ci-dockerfiles/llvm-6.0.0/Dockerfile b/.ci-dockerfiles/llvm-6.0.0/Dockerfile
new file mode 100644
index 0000000000..07c0b42c44
--- /dev/null
+++ b/.ci-dockerfiles/llvm-6.0.0/Dockerfile
@@ -0,0 +1,27 @@
+FROM ubuntu:14.04
+
+ENV LLVM_VERSION 6.0.0
+
+RUN apt-get update \
+ && apt-get install -y \
+  apt-transport-https \
+  build-essential \
+  g++ \
+  git \
+  libncurses5-dev \
+  libssl-dev \
+  make \
+  wget \
+  xz-utils \
+  zlib1g-dev \
+ && cd /tmp \
+ && wget ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre2-10.21.tar.bz2 \
+ && tar xjvf pcre2-10.21.tar.bz2 \
+ && cd pcre2-10.21 \
+ && ./configure --prefix=/usr \
+ && make \
+ && sudo make install \
+ && cd / \
+ && rm -rf /tmp/pcre* \
+ && wget -O - http://releases.llvm.org/${LLVM_VERSION}/clang+llvm-${LLVM_VERSION}-x86_64-linux-gnu-ubuntu-14.04.tar.xz \
+ | tar xJf - --no-same-owner --strip-components 1 -C /usr/local/ clang+llvm-${LLVM_VERSION}-x86_64-linux-gnu-ubuntu-14.04
diff --git a/.ci-dockerfiles/llvm-6.0.0/README.md b/.ci-dockerfiles/llvm-6.0.0/README.md
new file mode 100644
index 0000000000..7169658023
--- /dev/null
+++ b/.ci-dockerfiles/llvm-6.0.0/README.md
@@ -0,0 +1,21 @@
+# Build image
+
+```bash
+docker build -t ponylang/ponyc-ci:llvm-6.0.0 .
+```
+
+# Run image to test
+
+Will get you a bash shell in the image to try cloning Pony into where you can test a build to make sure everything will work before pushing
+
+```bash
+docker run --name ponyc-ci-llvm-600 --rm -i -t ponylang/ponyc-ci:llvm-6.0.0 bash
+```
+
+# Push to dockerhub
+
+You'll need credentials for the ponylang dockerhub account. Talk to @jemc or @seantallen for access
+
+```bash
+docker push ponylang/ponyc-ci:llvm-6.0.0
+```
diff --git a/.circleci/config.yml b/.circleci/config.yml
index 57c9a8554e..7d1535f310 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -12,6 +12,18 @@ jobs:
     steps:
       - checkout
       - run: find . -name '*.bash' -exec shellcheck {} \;
+  llvm-600-debug:
+    docker:
+      - image: ponylang/ponyc-ci:llvm-6.0.0
+    steps:
+      - checkout
+      - run: make test-ci config=debug default_pic=true
+  llvm-600-release:
+    docker:
+      - image: ponylang/ponyc-ci:llvm-6.0.0
+    steps:
+      - checkout
+      - run: make test-ci config=release default_pic=true
   llvm-501-debug:
     docker:
       - image: ponylang/ponyc-ci:llvm-5.0.1
@@ -73,6 +85,8 @@ workflows:
     jobs:
       - verify-changelog
       - validate-shell-scripts
+      - llvm-600-debug
+      - llvm-600-release
       - llvm-501-debug
       - llvm-501-release
       - llvm-401-debug
diff --git a/.travis_script.bash b/.travis_script.bash
index 1b35672b6c..f8d817a98c 100644
--- a/.travis_script.bash
+++ b/.travis_script.bash
@@ -49,24 +49,6 @@ case "${TRAVIS_OS_NAME}" in
       make clean
       brew uninstall llvm@3.9
 
-      # 4.0.x
-      brew install llvm@4
-      brew link --overwrite --force llvm@4
-      ln -fs "$(which llvm-config)" llvmsym/llvm-config-4.0
-      ln -fs "$(which clang++)" llvmsym/clang++-4.0
-
-      export CC1=clang-4.0
-      export CXX1=clang++-4.0
-      #echo "Running LLVM 4.0 config=debug build..."
-      #export config=debug
-      #ponyc-test
-      echo "Running LLVM 4.0 config=release build..."
-      export config=release
-      ponyc-test
-
-      make clean
-      brew uninstall llvm@4
-
       # 5.0.x
       brew install llvm@5
       brew link --overwrite --force llvm@5
@@ -75,15 +57,31 @@ case "${TRAVIS_OS_NAME}" in
 
       export CC1=clang-5.0
       export CXX1=clang++-5.0
-      #echo "Running LLVM 5.0 config=debug build..."
-      #export config=debug
-      #ponyc-test
       echo "Running LLVM 5.0 config=release build..."
       export config=release
       ponyc-test
 
       make clean
       brew uninstall llvm@5
+
+      # 6.0.x
+      # There is no llvm@6 package right now, so this will break once LLVM 7
+      # is released. Hopefully when they do that there will be a llvm@6 package
+      # at which point both `brew install llvm` and `brew uninstall llvm`
+      # should be updated to replace `llvm` with `llvm@6`
+      brew install llvm
+      brew link --overwrite --force llvm
+      ln -fs "$(which llvm-config)" llvmsym/llvm-config-6.0
+      ln -fs "$(which clang++)" llvmsym/clang++-6.0
+
+      export CC1=clang-6.0
+      export CXX1=clang++-6.0
+      echo "Running LLVM 6.0 config=release build..."
+      export config=release
+      ponyc-test
+
+      make clean
+      brew uninstall llvm
     fi
   ;;
 
diff --git a/Makefile b/Makefile
index df74153e29..95adaab3c7 100644
--- a/Makefile
+++ b/Makefile
@@ -205,6 +205,8 @@ endif
 ifndef LLVM_CONFIG
   ifneq (,$(shell which /usr/local/opt/llvm/bin/llvm-config 2> /dev/null))
     LLVM_CONFIG = /usr/local/opt/llvm/bin/llvm-config
+  else ifneq (,$(shell which llvm-config-6.0 2> /dev/null))
+    LLVM_CONFIG = llvm-config-6.0
   else ifneq (,$(shell which llvm-config-3.9 2> /dev/null))
     LLVM_CONFIG = llvm-config-3.9
   else ifneq (,$(shell which /usr/local/opt/llvm@3.9/bin/llvm-config 2> /dev/null))
@@ -261,6 +263,8 @@ else ifeq ($(llvm_version),5.0.0)
   $(warning WARNING: LLVM 5 support is experimental and may result in decreased performance or crashes)
 else ifeq ($(llvm_version),5.0.1)
   $(warning WARNING: LLVM 5 support is experimental and may result in decreased performance or crashes)
+else ifeq ($(llvm_version),6.0.0)
+  $(warning WARNING: LLVM 6 support is experimental and may result in decreased performance or crashes)
 else
   $(warning WARNING: Unsupported LLVM version: $(llvm_version))
   $(warning Please use LLVM 3.9.1)
@@ -615,12 +619,12 @@ define CONFIGURE_COMPILER
     compiler := $(CC)
     flags := $(ALL_CFLAGS) $(CFLAGS)
   endif
-  
+
   ifeq ($(suffix $(1)),.bc)
     compiler := $(CC)
     flags := $(ALL_CFLAGS) $(CFLAGS)
   endif
-  
+
   ifeq ($(suffix $(1)),.ll)
     compiler := $(CC)
     flags := $(ALL_CFLAGS) $(CFLAGS) -Wno-override-module
diff --git a/src/libponyc/codegen/codegen.c b/src/libponyc/codegen/codegen.c
index d3777636bc..9858f0c189 100644
--- a/src/libponyc/codegen/codegen.c
+++ b/src/libponyc/codegen/codegen.c
@@ -16,6 +16,9 @@
 #include "ponyassert.h"
 
 #include <platform.h>
+#if PONY_LLVM >= 600
+#include <llvm-c/DebugInfo.h>
+#endif
 #include <llvm-c/Initialization.h>
 #include <llvm-c/Linker.h>
 #include <llvm-c/Support.h>
@@ -672,10 +675,22 @@ static bool init_module(compile_t* c, ast_t* program, pass_opt_t* opt, bool jit)
   c->builder = LLVMCreateBuilderInContext(c->context);
   c->di = LLVMNewDIBuilder(c->module);
 
+#if PONY_LLVM < 600
   // TODO: what LANG id should be used?
   c->di_unit = LLVMDIBuilderCreateCompileUnit(c->di, 0x0004,
     package_filename(package), package_path(package), "ponyc-" PONY_VERSION,
     c->opt->release);
+#else
+  const char* filename = package_filename(package);
+  const char* dirname = package_path(package);
+  const char* version = "ponyc-" PONY_VERSION;
+  LLVMMetadataRef fileRef = LLVMDIBuilderCreateFile(c->di, filename,
+    strlen(filename), dirname, strlen(dirname));
+  c->di_unit = LLVMDIBuilderCreateCompileUnit(c->di,
+    LLVMDWARFSourceLanguageC_plus_plus, fileRef, version, strlen(version),
+    opt->release, "", 0, 0, "", 0, LLVMDWARFEmissionFull,
+    0, false, false);
+#endif
 
   // Empty frame stack.
   c->frame = NULL;
@@ -722,6 +737,14 @@ bool codegen_merge_runtime_bitcode(compile_t* c)
   return true;
 }
 
+#if PONY_LLVM == 600
+// TODO: remove for 6.0.1: https://reviews.llvm.org/D44140
+PONY_EXTERN_C_BEGIN
+extern void LLVMInitializeInstCombine_Pony(LLVMPassRegistryRef R);
+PONY_EXTERN_C_END
+#define LLVMInitializeInstCombine LLVMInitializeInstCombine_Pony
+#endif
+
 bool codegen_llvm_init()
 {
   LLVMLoadLibraryPermanently(NULL);
diff --git a/src/libponyc/codegen/gendebug.cc b/src/libponyc/codegen/gendebug.cc
index 655004ee67..f8eb5163ca 100644
--- a/src/libponyc/codegen/gendebug.cc
+++ b/src/libponyc/codegen/gendebug.cc
@@ -69,6 +69,7 @@ void LLVMDIBuilderDestroy(LLVMDIBuilderRef d)
   delete pd;
 }
 
+#if PONY_LLVM < 600
 void LLVMDIBuilderFinalize(LLVMDIBuilderRef d)
 {
   unwrap(d)->finalize();
@@ -101,6 +102,7 @@ LLVMMetadataRef LLVMDIBuilderCreateFile(LLVMDIBuilderRef d, const char* file)
 
   return wrap(pd->createFile(filename, dir));
 }
+#endif
 
 LLVMMetadataRef LLVMDIBuilderCreateNamespace(LLVMDIBuilderRef d,
   LLVMMetadataRef scope, const char* name, LLVMMetadataRef file, unsigned line)
diff --git a/src/libponyc/codegen/gendebug.h b/src/libponyc/codegen/gendebug.h
index ae03a0881c..32976d91dc 100644
--- a/src/libponyc/codegen/gendebug.h
+++ b/src/libponyc/codegen/gendebug.h
@@ -3,6 +3,9 @@
 
 #include <platform.h>
 #include <llvm-c/Core.h>
+#if PONY_LLVM >= 600
+#include <llvm-c/DebugInfo.h>
+#endif
 
 PONY_EXTERN_C_BEGIN
 
@@ -46,6 +49,7 @@ LLVMDIBuilderRef LLVMNewDIBuilder(LLVMModuleRef m);
 
 void LLVMDIBuilderDestroy(LLVMDIBuilderRef d);
 
+#if PONY_LLVM < 600
 void LLVMDIBuilderFinalize(LLVMDIBuilderRef d);
 
 LLVMMetadataRef LLVMDIBuilderCreateCompileUnit(LLVMDIBuilderRef d,
@@ -53,9 +57,10 @@ LLVMMetadataRef LLVMDIBuilderCreateCompileUnit(LLVMDIBuilderRef d,
   int optimized);
 
 LLVMMetadataRef LLVMDIBuilderCreateFile(LLVMDIBuilderRef d, const char* file);
+#endif
 
-LLVMMetadataRef LLVMDIBuilderCreateNamespace(LLVMDIBuilderRef d, 
-  LLVMMetadataRef scope, const char* name, LLVMMetadataRef file, 
+LLVMMetadataRef LLVMDIBuilderCreateNamespace(LLVMDIBuilderRef d,
+  LLVMMetadataRef scope, const char* name, LLVMMetadataRef file,
   unsigned line);
 
 LLVMMetadataRef LLVMDIBuilderCreateLexicalBlock(LLVMDIBuilderRef d,
diff --git a/src/libponyc/codegen/genopt.cc b/src/libponyc/codegen/genopt.cc
index d0e83d9d2d..6421cda33f 100644
--- a/src/libponyc/codegen/genopt.cc
+++ b/src/libponyc/codegen/genopt.cc
@@ -32,6 +32,10 @@
 #include <llvm/Transforms/Utils/Cloning.h>
 #include <llvm/ADT/SmallSet.h>
 
+#if PONY_LLVM >= 600
+#include <llvm-c/DebugInfo.h>
+#endif
+
 #include "../../libponyrt/mem/heap.h"
 #include "ponyassert.h"
 
@@ -87,6 +91,15 @@ static void print_transform(compile_t* c, Instruction* i, const char* s)
   }
 }
 
+// TODO: remove for 6.0.1: https://reviews.llvm.org/D44140
+#if PONY_LLVM == 600
+PONY_EXTERN_C_BEGIN
+void LLVMInitializeInstCombine_Pony(LLVMPassRegistryRef R) {
+  initializeInstructionCombiningPassPass(*unwrap(R));
+}
+PONY_EXTERN_C_END
+#endif
+
 class HeapToStack : public FunctionPass
 {
 public:
@@ -302,9 +315,9 @@ class HeapToStack : public FunctionPass
         }
 
         case Instruction::Load:
-          // This is a workaround for a problem with LLVM 4 & 5 on *nix when 
+          // This is a workaround for a problem with LLVM 4 & 5 on *nix when
           // hoisting loads (see #2303, #2061, #1592).
-          // TODO: figure out the real reason LLVM 4 and 5 produce bad code 
+          // TODO: figure out the real reason LLVM 4 and 5 produce bad code
           // when hoisting stack allocated loads.
 #if PONY_LLVM >= 400 && !defined(_MSC_VER)
           // fall through
diff --git a/src/libponyc/codegen/gentype.c b/src/libponyc/codegen/gentype.c
index 1f32b89514..300b51c887 100644
--- a/src/libponyc/codegen/gentype.c
+++ b/src/libponyc/codegen/gentype.c
@@ -20,6 +20,10 @@
 #include <stdlib.h>
 #include <string.h>
 
+#if PONY_LLVM >= 600
+#include <llvm-c/DebugInfo.h>
+#endif
+
 static size_t tbaa_metadata_hash(tbaa_metadata_t* a)
 {
   return ponyint_hash_ptr(a->name);
@@ -391,7 +395,11 @@ static void make_debug_info(compile_t* c, reach_type_t* t)
     file = "";
 
   compile_type_t* c_t = (compile_type_t*)t->c_type;
+#if PONY_LLVM < 600
   c_t->di_file = LLVMDIBuilderCreateFile(c->di, file);
+#else
+  c_t->di_file = LLVMDIBuilderCreateFile(c->di, file, strlen(file), "", 0);
+#endif
 
   switch(t->underlying)
   {
diff --git a/src/libponyc/codegen/host.cc b/src/libponyc/codegen/host.cc
index e9ee975ade..a1ea54de99 100644
--- a/src/libponyc/codegen/host.cc
+++ b/src/libponyc/codegen/host.cc
@@ -39,8 +39,6 @@ LLVMTargetMachineRef codegen_machine(LLVMTargetRef target, pass_opt_t* opt,
   if(opt->pic || opt->library)
     reloc = Reloc::PIC_;
 
-  CodeModel::Model model = jit ? CodeModel::JITDefault : CodeModel::Default;
-
   CodeGenOpt::Level opt_level =
     opt->release ? CodeGenOpt::Aggressive : CodeGenOpt::None;
 
@@ -49,8 +47,14 @@ LLVMTargetMachineRef codegen_machine(LLVMTargetRef target, pass_opt_t* opt,
 
   Target* t = reinterpret_cast<Target*>(target);
 
+#if PONY_LLVM < 600
+  CodeModel::Model model = jit ? CodeModel::JITDefault : CodeModel::Default;
   TargetMachine* m = t->createTargetMachine(opt->triple, opt->cpu,
     opt->features, options, reloc, model, opt_level);
+#else
+TargetMachine* m = t->createTargetMachine(opt->triple, opt->cpu,
+  opt->features, options, reloc, llvm::None, opt_level, jit);
+#endif
 
   return reinterpret_cast<LLVMTargetMachineRef>(m);
 }
@@ -105,7 +109,11 @@ char* LLVMGetHostCPUFeatures()
 
 void LLVMSetUnsafeAlgebra(LLVMValueRef inst)
 {
+#if PONY_LLVM < 600
   unwrap<Instruction>(inst)->setHasUnsafeAlgebra(true);
+#else // See https://reviews.llvm.org/D39304 for this change
+  unwrap<Instruction>(inst)->setHasAllowReassoc(true);
+#endif
 }
 
 void LLVMSetNoUnsignedWrap(LLVMValueRef inst)
diff --git a/wscript b/wscript
index 4a74cbd816..6336ef0790 100644
--- a/wscript
+++ b/wscript
@@ -50,13 +50,13 @@ MSVC_VERSIONS = [ '15.6', '15.4', '15.0', '14.0' ]
 # keep these in sync with the list in .appveyor.yml
 LLVM_VERSIONS = [
     '3.9.1',
-    '4.0.1',
-    '5.0.1'
+    '5.0.1',
+    '6.0.0'
 ]
 
-WINDOWS_LIBS_TAG = "v1.6.0"
+WINDOWS_LIBS_TAG = "v1.7.0"
 LIBRESSL_VERSION = "2.6.4"
-PCRE2_VERSION = "10.30"
+PCRE2_VERSION = "10.31"
 
 # Adds an option for specifying debug or release mode.
 def options(ctx):
@@ -259,8 +259,8 @@ def build(ctx):
 
     # build targets:
 
-    if ctx.options.llvm.startswith('4') or ctx.options.llvm.startswith('5'):
-        print('WARNING: LLVM 4 and 5 support is experimental and may result in decreased performance or crashes')
+    if ctx.options.llvm.startswith('4') or ctx.options.llvm.startswith('5') or ctx.options.llvm.startswith('6'):
+        print('WARNING: LLVM 4, 5 and 6 support is experimental and may result in decreased performance or crashes')
 
     # gtest
     ctx(