diff --git a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
--- a/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
+++ b/clang/lib/StaticAnalyzer/Core/LoopUnrolling.cpp
@@ -164,6 +164,11 @@
   if (VD->hasGlobalStorage())
     return true;
 
+  const bool isParm = VD->getKind() == Decl::ParmVar;
+  // Reference parameters are assumed as escaped variables.
+  if (isParm && VD->getType()->isReferenceType())
+    return true;
+
   while (!N->pred_empty()) {
     // FIXME: getStmtForDiagnostics() does nasty things in order to provide
     // a valid statement for body farms, do we need this behavior here?
@@ -193,6 +198,11 @@
 
     N = N->getFirstPred();
   }
+
+  // Parameter declaration will not be found.
+  if (isParm)
+    return false;
+
   llvm_unreachable("Reached root without finding the declaration of VD");
 }
 
diff --git a/clang/test/Analysis/loop-unrolling.cpp b/clang/test/Analysis/loop-unrolling.cpp
--- a/clang/test/Analysis/loop-unrolling.cpp
+++ b/clang/test/Analysis/loop-unrolling.cpp
@@ -499,3 +499,15 @@
     clang_analyzer_numTimesReached(); // expected-warning {{6}}
   }
 }
+
+void parm_by_value_as_loop_counter(int i) {
+  for (i = 0; i < 10; ++i) {
+    clang_analyzer_numTimesReached(); // expected-warning {{10}}
+  }
+}
+
+void parm_by_ref_as_loop_counter(int &i) {
+  for (i = 0; i < 10; ++i) {
+    clang_analyzer_numTimesReached(); // expected-warning {{4}}
+  }
+}