Index: lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp
===================================================================
--- lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp
+++ lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp
@@ -329,8 +329,8 @@
                                                     nullptr);
 }
 
-/// Returns true when the value stored at the given location is null
-/// and the passed in type is nonnnull.
+/// Returns true when the value stored at the given location has been
+/// constrained to null after being passed through an object of nonnnull type.
 static bool checkValueAtLValForInvariantViolation(ProgramStateRef State,
                                                   SVal LV, QualType T) {
   if (getNullabilityAnnotation(T) != Nullability::Nonnull)
@@ -340,9 +340,14 @@
   if (!RegionVal)
     return false;
 
-  auto StoredVal =
-  State->getSVal(RegionVal->getRegion()).getAs<DefinedOrUnknownSVal>();
-  if (!StoredVal)
+  // If the value was constrained to null *after* it was passed through that
+  // location, it could not have been a concrete pointer *when* it was passed.
+  // In that case we would have handled the situation when the value was
+  // bound to that location, by emitting (or not emitting) a report.
+  // Therefore we are only interested in symbolic regions that can be either
+  // null or non-null depending on the value of their respective symbol.
+  auto StoredVal = State->getSVal(*RegionVal).getAs<loc::MemRegionVal>();
+  if (!StoredVal || !isa<SymbolicRegion>(StoredVal->getRegion()))
     return false;
 
   if (getNullConstraint(*StoredVal, State) == NullConstraint::IsNull)
@@ -1170,10 +1175,15 @@
 
   NullabilityMapTy B = State->get<NullabilityMap>();
 
+  if (State->get<InvariantViolated>())
+    Out << Sep << NL
+        << "Nullability invariant was violated, warnings suppressed." << NL;
+
   if (B.isEmpty())
     return;
 
-  Out << Sep << NL;
+  if (!State->get<InvariantViolated>())
+    Out << Sep << NL;
 
   for (NullabilityMapTy::iterator I = B.begin(), E = B.end(); I != E; ++I) {
     Out << I->first << " : ";
Index: test/Analysis/nullability-arc.mm
===================================================================
--- test/Analysis/nullability-arc.mm
+++ test/Analysis/nullability-arc.mm
@@ -0,0 +1,39 @@
+// RUN: %clang_analyze_cc1 -w -analyzer-checker=core,nullability\
+// RUN:                       -analyzer-output=text -verify %s
+// RUN: %clang_analyze_cc1 -w -analyzer-checker=core,nullability\
+// RUN:                       -analyzer-output=text -verify %s -fobjc-arc
+
+#if !__has_feature(objc_arc)
+// expected-no-diagnostics
+#endif
+
+
+#define nil ((id)0)
+
+@interface Param
+@end
+
+@interface Base
+- (void)foo:(Param *_Nonnull)param;
+@end
+
+@interface Derived : Base
+@end
+
+@implementation Derived
+- (void)foo:(Param *)param {
+  // FIXME: Why do we not emit the warning under ARC?
+  [super foo:param];
+#if __has_feature(objc_arc)
+  // expected-warning@-2{{nil passed to a callee that requires a non-null 1st parameter}}
+  // expected-note@-3   {{nil passed to a callee that requires a non-null 1st parameter}}
+#endif
+
+  [self foo:nil];
+#if __has_feature(objc_arc)
+  // expected-note@-2{{Calling 'foo:'}}
+  // expected-note@-3{{Passing nil object reference via 1st parameter 'param'}}
+#endif
+}
+@end
+
Index: test/Analysis/nullability.mm
===================================================================
--- test/Analysis/nullability.mm
+++ test/Analysis/nullability.mm
@@ -1,5 +1,36 @@
-// RUN: %clang_analyze_cc1 -fblocks -analyzer-checker=core,nullability.NullPassedToNonnull,nullability.NullReturnedFromNonnull,nullability.NullablePassedToNonnull,nullability.NullableReturnedFromNonnull,nullability.NullableDereferenced -DNOSYSTEMHEADERS=0 -verify %s
-// RUN: %clang_analyze_cc1 -fblocks -analyzer-checker=core,nullability.NullPassedToNonnull,nullability.NullReturnedFromNonnull,nullability.NullablePassedToNonnull,nullability.NullableReturnedFromNonnull,nullability.NullableDereferenced -analyzer-config nullability:NoDiagnoseCallsToSystemHeaders=true -DNOSYSTEMHEADERS=1 -verify %s
+// RUN: %clang_analyze_cc1 -fblocks -verify %s -analyzer-checker=core \
+// RUN:   -analyzer-checker=nullability.NullPassedToNonnull \
+// RUN:   -analyzer-checker=nullability.NullReturnedFromNonnull \
+// RUN:   -analyzer-checker=nullability.NullablePassedToNonnull \
+// RUN:   -analyzer-checker=nullability.NullableReturnedFromNonnull \
+// RUN:   -analyzer-checker=nullability.NullableDereferenced \
+// RUN:   -DNOSYSTEMHEADERS=0
+
+// RUN: %clang_analyze_cc1 -fblocks -verify %s -analyzer-checker=core \
+// RUN:   -analyzer-checker=nullability.NullPassedToNonnull \
+// RUN:   -analyzer-checker=nullability.NullReturnedFromNonnull \
+// RUN:   -analyzer-checker=nullability.NullablePassedToNonnull \
+// RUN:   -analyzer-checker=nullability.NullableReturnedFromNonnull \
+// RUN:   -analyzer-checker=nullability.NullableDereferenced \
+// RUN:   -DNOSYSTEMHEADERS=1 \
+// RUN:   -analyzer-config nullability:NoDiagnoseCallsToSystemHeaders=true
+
+// RUN: %clang_analyze_cc1 -fblocks -verify %s -analyzer-checker=core\
+// RUN:   -analyzer-checker=nullability.NullPassedToNonnull\
+// RUN:   -analyzer-checker=nullability.NullReturnedFromNonnull\
+// RUN:   -analyzer-checker=nullability.NullablePassedToNonnull\
+// RUN:   -analyzer-checker=nullability.NullableReturnedFromNonnull\
+// RUN:   -analyzer-checker=nullability.NullableDereferenced\
+// RUN:   -DNOSYSTEMHEADERS=0 -fobjc-arc
+
+// RUN: %clang_analyze_cc1 -fblocks -verify %s -analyzer-checker=core\
+// RUN:   -analyzer-checker=nullability.NullPassedToNonnull\
+// RUN:   -analyzer-checker=nullability.NullReturnedFromNonnull\
+// RUN:   -analyzer-checker=nullability.NullablePassedToNonnull\
+// RUN:   -analyzer-checker=nullability.NullableReturnedFromNonnull\
+// RUN:   -analyzer-checker=nullability.NullableDereferenced\
+// RUN:   -DNOSYSTEMHEADERS=1 -fobjc-arc\
+// RUN:   -analyzer-config nullability:NoDiagnoseCallsToSystemHeaders=true
 
 #include "Inputs/system-header-simulator-for-nullability.h"