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
@@ -160,8 +160,13 @@
 }
 
 static bool isPossiblyEscaped(const VarDecl *VD, ExplodedNode *N) {
-  // Global variables and parameters assumed as escaped variables.
-  if (VD->hasGlobalStorage() || VD->getKind() == Decl::ParmVar)
+  // Global variables assumed as escaped variables.
+  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()) {
@@ -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
@@ -500,8 +500,14 @@
   }
 }
 
-void arg_as_loop_counter(int i) {
+void parm_by_value_as_loop_counter(int i) {
   for (i = 0; i < 10; ++i) {
-    (void)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}}
   }
 }