Index: clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
+++ clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
@@ -1340,13 +1340,12 @@
 static void showBRParamDiagnostics(llvm::raw_svector_ostream &OS,
                                    StoreInfo SI) {
   const auto *VR = cast<VarRegion>(SI.Dest);
-  const auto *Param = cast<ParmVarDecl>(VR->getDecl());
+  const auto *D = VR->getDecl();
 
   OS << "Passing ";
 
   if (isa<loc::ConcreteInt>(SI.Value)) {
-    OS << (isObjCPointer(Param) ? "nil object reference"
-                                : "null pointer value");
+    OS << (isObjCPointer(D) ? "nil object reference" : "null pointer value");
 
   } else if (SI.Value.isUndef()) {
     OS << "uninitialized value";
@@ -1361,12 +1360,29 @@
     OS << "value";
   }
 
-  // Printed parameter indexes are 1-based, not 0-based.
-  unsigned Idx = Param->getFunctionScopeIndex() + 1;
-  OS << " via " << Idx << llvm::getOrdinalSuffix(Idx) << " parameter";
-  if (VR->canPrintPretty()) {
-    OS << " ";
-    VR->printPretty(OS);
+  if (const auto *Param = dyn_cast<ParmVarDecl>(VR->getDecl())) {
+    // Printed parameter indexes are 1-based, not 0-based.
+    unsigned Idx = Param->getFunctionScopeIndex() + 1;
+    OS << " via " << Idx << llvm::getOrdinalSuffix(Idx) << " parameter";
+    if (VR->canPrintPretty()) {
+      OS << " ";
+      VR->printPretty(OS);
+    }
+  } else if (const auto *ImplParam = dyn_cast<ImplicitParamDecl>(D)) {
+    switch (ImplParam->getParameterKind()) {
+    case ImplicitParamDecl::ImplicitParamKind::ObjCSelf:
+      OS << " via implicit parameter 'self'";
+      break;
+    case ImplicitParamDecl::ImplicitParamKind::CXXThis:
+      OS << " via implicit parameter 'this'";
+      break;
+    case ImplicitParamDecl::ImplicitParamKind::ObjCCmd:
+    case ImplicitParamDecl::ImplicitParamKind::CXXVTT:
+    case ImplicitParamDecl::ImplicitParamKind::CapturedContext:
+    case ImplicitParamDecl::ImplicitParamKind::ThreadPrivateVar:
+    case ImplicitParamDecl::ImplicitParamKind::Other:
+      break;
+    };
   }
 }
 
Index: clang/test/Analysis/path-notes-impl-param.m
===================================================================
--- /dev/null
+++ clang/test/Analysis/path-notes-impl-param.m
@@ -0,0 +1,31 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,osx.cocoa.RetainCount -analyzer-output=text -verify %s
+
+@protocol NSObject
+@end
+
+@interface NSObject <NSObject> {}
+- (id)init;
++ (id)alloc;
+- (id)autorelease;
+@end
+
+@interface Foo : NSObject
+@property(nonatomic) int bar;
+@end
+
+@implementation Foo
+-(int)bar {
+  return 0;
+}
+@end
+
+int baz() {
+  Foo *f = [Foo alloc];
+  // expected-note@-1 {{'f' initialized here}}
+  // expected-note@-2 {{Method returns an instance of Foo with a +1 retain count}}
+
+  return f.bar;
+  // expected-warning@-1 {{Potential leak of an object stored into 'self' [osx.cocoa.RetainCount]}}
+  // expected-note@-2 {{Passing value via implicit parameter 'self'}}
+  // expected-note@-3 {{Object leaked: object allocated and stored into 'self' is not referenced later in this execution path and has a retain count of +1}}
+}