diff --git a/include/clang/Analysis/CallGraph.h b/include/clang/Analysis/CallGraph.h
index b8ae67c..a2a27a8 100644
--- a/include/clang/Analysis/CallGraph.h
+++ b/include/clang/Analysis/CallGraph.h
@@ -98,7 +98,7 @@
   bool VisitFunctionDecl(FunctionDecl *FD) {
     // We skip function template definitions, as their semantics is
     // only determined when they are instantiated.
-    if (includeInGraph(FD)) {
+    if (includeInGraph(FD) && FD->isThisDeclarationADefinition()) {
       // Add all blocks declared inside this function to the graph.
       addNodesForBlocks(FD);
       // If this function has external linkage, anything could call it.
diff --git a/test/Analysis/debug-CallGraph.c b/test/Analysis/debug-CallGraph.c
index 686abb0..3488227 100644
--- a/test/Analysis/debug-CallGraph.c
+++ b/test/Analysis/debug-CallGraph.c
@@ -43,8 +43,18 @@
 void eee() {}
 void fff() { eee(); }
 
+// This test case tests that forward declaration for the top-level function
+// does not affect call graph construction.
+void do_nothing() {}
+void test_single_call();
+void test_single_call() {
+  do_nothing();
+}
+
 // CHECK:--- Call graph Dump ---
-// CHECK-NEXT: {{Function: < root > calls: get5 add test_add mmm foo aaa < > bbb ccc ddd eee fff $}}
+// CHECK-NEXT: {{Function: < root > calls: get5 add test_add mmm foo aaa < > bbb ddd ccc eee fff do_nothing test_single_call $}}
+// CHECK-NEXT: {{Function: test_single_call calls: do_nothing $}}
+// CHECK-NEXT: {{Function: do_nothing calls: $}}
 // CHECK-NEXT: {{Function: fff calls: eee $}}
 // CHECK-NEXT: {{Function: eee calls: $}}
 // CHECK-NEXT: {{Function: ddd calls: ccc $}}