Index: test/lit.cfg
===================================================================
--- test/lit.cfg
+++ test/lit.cfg
@@ -267,8 +267,12 @@
                           pattern)
     tool_pipe = tool_match.group(2)
     tool_name = tool_match.group(4)
-    tool_path = lit.util.which(tool_name, llvm_tools_dir)
-    if not tool_path:
+    # Did the user specify the tool path + arguments? This allows things like
+    # llvm-lit "-Dllc=llc -enable-misched -verify-machineinstrs"
+    tool_path = lit_config.params.get(tool_name)
+    if tool_path is None:
+        tool_path = lit.util.which(tool_name, llvm_tools_dir)
+    if tool_path is None:
         # Warn, but still provide a substitution.
         lit_config.note('Did not find ' + tool_name + ' in ' + llvm_tools_dir)
         tool_path = llvm_tools_dir + '/' + tool_name
Index: utils/lit/lit/main.py
===================================================================
--- utils/lit/lit/main.py
+++ utils/lit/lit/main.py
@@ -146,7 +146,7 @@
     parser.add_option("", "--config-prefix", dest="configPrefix",
                       metavar="NAME", help="Prefix for 'lit' config files",
                       action="store", default=None)
-    parser.add_option("", "--param", dest="userParameters",
+    parser.add_option("-D", "--param", dest="userParameters",
                       metavar="NAME=VAL",
                       help="Add 'NAME' = 'VAL' to the user defined parameters",
                       type=str, action="append", default=[])