diff --git a/alloy.py b/alloy.py
index 525f90d0..657e67bf 100755
--- a/alloy.py
+++ b/alloy.py
@@ -88,6 +88,9 @@ def build_LLVM(version_LLVM, revision, folder, tarball, debug, selfbuild, extra,
     FOLDER_NAME=version_LLVM
     if  version_LLVM == "trunk":
         SVN_PATH="trunk"
+    if  version_LLVM == "3.4":
+        SVN_PATH="tags/RELEASE_34/rc1"
+        version_LLVM = "3_4"
     if  version_LLVM == "3.3":
         SVN_PATH="tags/RELEASE_33/final"
         version_LLVM = "3_3"
@@ -273,8 +276,10 @@ def build_ispc(version_LLVM, make):
         os.environ["LLVM_INSTALL_DIR"] = os.environ["LLVM_HOME"] + "\\bin-" + version_LLVM
         if version_LLVM == "3.3":
             temp = "3_3"
-        if version_LLVM == "trunk":
+        if version_LLVM == "3.4":
             temp = "3_4"
+        if version_LLVM == "trunk":
+            temp = "3_5"
         os.environ["LLVM_VERSION"] = "LLVM_" + temp
         try_do_LLVM("clean ISPC for building", "msbuild ispc.vcxproj /t:clean", True)
         try_do_LLVM("build ISPC with LLVM version " + version_LLVM + " ", "msbuild ispc.vcxproj /V:m /p:Platform=Win32 /p:Configuration=Release /t:rebuild", True)
@@ -376,7 +381,7 @@ def validation_run(only, only_targets, reference_branch, number, notify, update,
             archs.append("x86-64")
         if "native" in only:
             sde_targets_t = []
-        for i in ["3.1", "3.2", "3.3", "trunk"]:
+        for i in ["3.1", "3.2", "3.3", "3.4", "trunk"]:
             if i in only:
                 LLVM.append(i)
         if "current" in only:
@@ -676,7 +681,7 @@ if __name__ == '__main__':
     llvm_group = OptionGroup(parser, "Options for building LLVM",
                     "These options must be used with -b option.")
     llvm_group.add_option('--version', dest='version',
-        help='version of llvm to build: 3.1 3.2 3.3 trunk. Default: trunk', default="trunk")
+        help='version of llvm to build: 3.1 3.2 3.3 3.4 trunk. Default: trunk', default="trunk")
     llvm_group.add_option('--revision', dest='revision',
         help='revision of llvm to build in format r172870', default="")
     llvm_group.add_option('--debug', dest='debug',
@@ -711,7 +716,7 @@ if __name__ == '__main__':
     run_group.add_option('--only', dest='only',
         help='set types of tests. Possible values:\n' + 
             '-O0, -O2, x86, x86-64, stability (test only stability), performance (test only performance)\n' +
-            'build (only build with different LLVM), 3.1, 3.2, 3.3, trunk, native (do not use SDE), current (do not rebuild ISPC).',
+            'build (only build with different LLVM), 3.1, 3.2, 3.3, 3.4, trunk, native (do not use SDE), current (do not rebuild ISPC).',
             default="")
     run_group.add_option('--perf_LLVM', dest='perf_llvm',
         help='compare LLVM 3.3 with "--compare-with", default trunk', default=False, action='store_true')
diff --git a/run_tests.py b/run_tests.py
index 3f03cc9b..e6429861 100755
--- a/run_tests.py
+++ b/run_tests.py
@@ -452,7 +452,7 @@ def verify():
     f_lines = f.readlines()
     f.close()
     check = [["g++", "clang++", "cl"],["-O0", "-O2"],["x86","x86-64"],
-             ["Linux","Windows","Mac"],["LLVM 3.1","LLVM 3.2","LLVM 3.3","LLVM head"],
+             ["Linux","Windows","Mac"],["LLVM 3.1","LLVM 3.2","LLVM 3.3","LLVM 3.4","LLVM trunk"],
              ["sse2-i32x4", "sse2-i32x8", "sse4-i32x4", "sse4-i32x8", "sse4-i16x8",
               "sse4-i8x16", "avx1-i32x4" "avx1-i32x8", "avx1-i32x16", "avx1-i64x4", "avx1.1-i32x8",
               "avx1.1-i32x16", "avx1.1-i64x4", "avx2-i32x8", "avx2-i32x16", "avx2-i64x4",