Index: lib/Passes/PassBuilder.cpp
===================================================================
--- lib/Passes/PassBuilder.cpp
+++ lib/Passes/PassBuilder.cpp
@@ -1239,6 +1239,90 @@
   return Count;
 }
 
+static bool checkParametrizedPassName(StringRef Name, StringRef PassName) {
+  if (!Name.consume_front(PassName))
+    return false;
+  // normal pass name w/o parameters == default parameters
+  if (Name.empty())
+    return true;
+  return Name.consume_front("<") && Name.consume_back(">");
+}
+
+namespace {
+
+/// This performs customized parsing of pass name with parameters.
+///
+/// We do not need parametrization of passes in textual pipeline very often,
+/// yet on a rare occasion ability to specify parameters right there can be
+/// useful.
+template <typename ParserT>
+Expected<typename ParserT::ParametersT>
+parsePassParameters(ParserT &&Parser, StringRef Name, StringRef PassName) {
+  StringRef Params = Name;
+  if (!Params.consume_front(PassName)) {
+    assert(false && "unexpected failure to parse parametrized pass name");
+  }
+  // default parameters
+  if (Params.empty())
+    return typename ParserT::ParametersT{};
+
+  if (!Params.consume_front("<") || !Params.consume_back(">")) {
+    assert(false && "invalid format for parametrized pass name");
+  }
+
+  if (Error Err = Parser.parse(Params)) {
+    assert(Err.isA<StringError>() &&
+           "Pass parameter parser can only return StringErrors.");
+    return Err;
+  }
+  return Parser.getParameters();
+}
+
+/// Parser of parameters for LoopUnroll pass.
+struct LoopUnrollOptionsParser {
+  using ParametersT = LoopUnrollOptions;
+
+  LoopUnrollOptions UnrollOpts;
+
+  ParametersT getParameters() { return UnrollOpts; }
+  Error parse(StringRef);
+};
+
+Error LoopUnrollOptionsParser::parse(StringRef Params) {
+  while (!Params.empty()) {
+    StringRef ParamName;
+    std::tie(ParamName, Params) = Params.split(';');
+    int OptLevel = StringSwitch<int>(ParamName)
+                       .Case("O0", 0)
+                       .Case("O1", 1)
+                       .Case("O2", 2)
+                       .Case("O3", 3)
+                       .Default(-1);
+    if (OptLevel >= 0) {
+      UnrollOpts.setOptLevel(OptLevel);
+      continue;
+    }
+
+    bool Enable = !ParamName.consume_front("no-");
+    if (ParamName == "partial") {
+      UnrollOpts.setPartial(Enable);
+    } else if (ParamName == "peeling") {
+      UnrollOpts.setPeeling(Enable);
+    } else if (ParamName == "runtime") {
+      UnrollOpts.setRuntime(Enable);
+    } else if (ParamName == "upperbound") {
+      UnrollOpts.setUpperBound(Enable);
+    } else {
+      return make_error<StringError>(
+          formatv("invalid LoopUnrollPass parameter '{0}' ", ParamName).str(),
+          inconvertibleErrorCode());
+    }
+  }
+  return Error::success();
+}
+
+} // namespace
+
 /// Tests whether a pass name starts with a valid prefix for a default pipeline
 /// alias.
 static bool startsWithDefaultPipelineAliasPrefix(StringRef Name) {
@@ -1334,6 +1418,9 @@
 #define FUNCTION_PASS(NAME, CREATE_PASS)                                       \
   if (Name == NAME)                                                            \
     return true;
+#define FUNCTION_PASS_PARAMETRIZED(NAME, CREATE_PASS, PARSER)                  \
+  if (checkParametrizedPassName(Name, NAME))                                   \
+    return true;
 #define FUNCTION_ANALYSIS(NAME, CREATE_PASS)                                   \
   if (Name == "require<" NAME ">" || Name == "invalidate<" NAME ">")           \
     return true;
@@ -1671,6 +1758,14 @@
     FPM.addPass(CREATE_PASS);                                                  \
     return Error::success();                                                   \
   }
+#define FUNCTION_PASS_PARAMETRIZED(NAME, CREATE_PASS, PARSER)                  \
+  if (checkParametrizedPassName(Name, NAME)) {                                 \
+    auto Params = parsePassParameters(PARSER, Name, NAME);                     \
+    if (!Params)                                                               \
+      return Params.takeError();                                               \
+    FPM.addPass(CREATE_PASS(Params.get()));                                    \
+    return Error::success();                                                   \
+  }
 #define FUNCTION_ANALYSIS(NAME, CREATE_PASS)                                   \
   if (Name == "require<" NAME ">") {                                           \
     FPM.addPass(                                                               \
Index: lib/Passes/PassRegistry.def
===================================================================
--- lib/Passes/PassRegistry.def
+++ lib/Passes/PassRegistry.def
@@ -145,6 +145,9 @@
 #ifndef FUNCTION_PASS
 #define FUNCTION_PASS(NAME, CREATE_PASS)
 #endif
+#ifndef FUNCTION_PASS_PARAMETRIZED
+#define FUNCTION_PASS_PARAMETRIZED(NAME, CREATE_PASS, PARSER)
+#endif
 FUNCTION_PASS("aa-eval", AAEvaluator())
 FUNCTION_PASS("adce", ADCEPass())
 FUNCTION_PASS("add-discriminators", AddDiscriminatorsPass())
@@ -221,8 +224,9 @@
 FUNCTION_PASS("sroa", SROA())
 FUNCTION_PASS("tailcallelim", TailCallElimPass())
 FUNCTION_PASS("unreachableblockelim", UnreachableBlockElimPass())
-FUNCTION_PASS("unroll", LoopUnrollPass())
-FUNCTION_PASS("unroll<peeling;no-runtime>",LoopUnrollPass(LoopUnrollOptions().setPeeling(true).setRuntime(false)))
+FUNCTION_PASS_PARAMETRIZED("unroll", \
+			   [](LoopUnrollOptions Opts) { return LoopUnrollPass(Opts); }, \
+			   LoopUnrollOptionsParser())
 FUNCTION_PASS("verify", VerifierPass())
 FUNCTION_PASS("verify<domtree>", DominatorTreeVerifierPass())
 FUNCTION_PASS("verify<loops>", LoopVerifierPass())
@@ -232,6 +236,7 @@
 FUNCTION_PASS("view-cfg-only", CFGOnlyViewerPass())
 FUNCTION_PASS("transform-warning", WarnMissedTransformationsPass())
 #undef FUNCTION_PASS
+#undef FUNCTION_PASS_PARAMETRIZED
 
 #ifndef LOOP_ANALYSIS
 #define LOOP_ANALYSIS(NAME, CREATE_PASS)