Index: clang/lib/AST/JSONNodeDumper.cpp
===================================================================
--- clang/lib/AST/JSONNodeDumper.cpp
+++ clang/lib/AST/JSONNodeDumper.cpp
@@ -111,9 +111,14 @@
   if (const auto *ND = dyn_cast<NamedDecl>(D))
     attributeOnlyIfTrue("isHidden", ND->isHidden());
 
-  if (D->getLexicalDeclContext() != D->getDeclContext())
-    JOS.attribute("parentDeclContext",
-                  createPointerRepresentation(D->getDeclContext()));
+  if (D->getLexicalDeclContext() != D->getDeclContext()) {
+    // Because of multiple inheritance, a DeclContext pointer does not produce
+    // the same pointer representation as a Decl pointer that references the
+    // same AST Node.
+    const auto *ParentDeclContextDecl = dyn_cast<Decl>(D->getDeclContext());
+    JOS.attribute("parentDeclContextId",
+                  createPointerRepresentation(ParentDeclContextDecl));
+  }
 
   addPreviousDeclaration(D);
   InnerDeclVisitor::Visit(D);
Index: clang/test/AST/ast-dump-decl-context-json.cpp
===================================================================
--- /dev/null
+++ clang/test/AST/ast-dump-decl-context-json.cpp
@@ -0,0 +1,286 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -ast-dump=json -ast-dump-filter Test %s | FileCheck %s
+
+namespace Test {
+
+namespace NS {
+void Function();
+}
+void NS::Function() {}
+
+struct S {
+  void Method();
+};
+void S::Method() {}
+
+} // namespace Test
+
+// CHECK:  "kind": "NamespaceDecl",
+// CHECK-NEXT:  "loc": {
+// CHECK-NEXT:   "file": "{{.*}}",
+// CHECK-NEXT:   "line": 3,
+// CHECK-NEXT:   "col": 11,
+// CHECK-NEXT:   "tokLen": 4
+// CHECK-NEXT:  },
+// CHECK-NEXT:  "range": {
+// CHECK-NEXT:   "begin": {
+// CHECK-NEXT:    "col": 1,
+// CHECK-NEXT:    "tokLen": 9
+// CHECK-NEXT:   },
+// CHECK-NEXT:   "end": {
+// CHECK-NEXT:    "line": 15,
+// CHECK-NEXT:    "col": 1,
+// CHECK-NEXT:    "tokLen": 1
+// CHECK-NEXT:   }
+// CHECK-NEXT:  },
+// CHECK-NEXT:  "name": "Test",
+// CHECK-NEXT:  "inner": [
+// CHECK-NEXT:   {
+// CHECK-NEXT:    "id": "0x[[NS_ID:.*]]",
+// CHECK-NEXT:    "kind": "NamespaceDecl",
+// CHECK-NEXT:    "loc": {
+// CHECK-NEXT:     "line": 5,
+// CHECK-NEXT:     "col": 11,
+// CHECK-NEXT:     "tokLen": 2
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "range": {
+// CHECK-NEXT:     "begin": {
+// CHECK-NEXT:      "col": 1,
+// CHECK-NEXT:      "tokLen": 9
+// CHECK-NEXT:     },
+// CHECK-NEXT:     "end": {
+// CHECK-NEXT:      "line": 7,
+// CHECK-NEXT:      "col": 1,
+// CHECK-NEXT:      "tokLen": 1
+// CHECK-NEXT:     }
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "name": "NS",
+// CHECK-NEXT:    "inner": [
+// CHECK-NEXT:     {
+// CHECK-NEXT:      "id": "0x[[FUNCTION_ID:.*]]",
+// CHECK-NEXT:      "kind": "FunctionDecl",
+// CHECK-NEXT:      "loc": {
+// CHECK-NEXT:       "line": 6,
+// CHECK-NEXT:       "col": 6,
+// CHECK-NEXT:       "tokLen": 8
+// CHECK-NEXT:      },
+// CHECK-NEXT:      "range": {
+// CHECK-NEXT:       "begin": {
+// CHECK-NEXT:        "col": 1,
+// CHECK-NEXT:        "tokLen": 4
+// CHECK-NEXT:       },
+// CHECK-NEXT:       "end": {
+// CHECK-NEXT:        "col": 15,
+// CHECK-NEXT:        "tokLen": 1
+// CHECK-NEXT:       }
+// CHECK-NEXT:      },
+// CHECK-NEXT:      "name": "Function",
+// CHECK-NEXT:      "type": {
+// CHECK-NEXT:       "qualType": "void ()"
+// CHECK-NEXT:      }
+// CHECK-NEXT:     }
+// CHECK-NEXT:    ]
+// CHECK-NEXT:   },
+// CHECK-NEXT:   {
+// CHECK-NEXT:    "id": "0x{{.*}}",
+// CHECK-NEXT:    "kind": "FunctionDecl",
+// CHECK-NEXT:    "loc": {
+// CHECK-NEXT:     "line": 8,
+// CHECK-NEXT:     "col": 10,
+// CHECK-NEXT:     "tokLen": 8
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "range": {
+// CHECK-NEXT:     "begin": {
+// CHECK-NEXT:      "col": 1,
+// CHECK-NEXT:      "tokLen": 4
+// CHECK-NEXT:     },
+// CHECK-NEXT:     "end": {
+// CHECK-NEXT:      "col": 22,
+// CHECK-NEXT:      "tokLen": 1
+// CHECK-NEXT:     }
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "parentDeclContextId": "0x[[NS_ID]]",
+// CHECK-NEXT:    "previousDecl": "0x[[FUNCTION_ID]]",
+// CHECK-NEXT:    "name": "Function",
+// CHECK-NEXT:    "type": {
+// CHECK-NEXT:     "qualType": "void ()"
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "inner": [
+// CHECK-NEXT:     {
+// CHECK-NEXT:      "id": "0x{{.*}}",
+// CHECK-NEXT:      "kind": "CompoundStmt",
+// CHECK-NEXT:      "range": {
+// CHECK-NEXT:       "begin": {
+// CHECK-NEXT:        "col": 21,
+// CHECK-NEXT:        "tokLen": 1
+// CHECK-NEXT:       },
+// CHECK-NEXT:       "end": {
+// CHECK-NEXT:        "col": 22,
+// CHECK-NEXT:        "tokLen": 1
+// CHECK-NEXT:       }
+// CHECK-NEXT:      }
+// CHECK-NEXT:     }
+// CHECK-NEXT:    ]
+// CHECK-NEXT:   },
+// CHECK-NEXT:   {
+// CHECK-NEXT:    "id": "0x[[S_ID:.*]]",
+// CHECK-NEXT:    "kind": "CXXRecordDecl",
+// CHECK-NEXT:    "loc": {
+// CHECK-NEXT:     "line": 10,
+// CHECK-NEXT:     "col": 8,
+// CHECK-NEXT:     "tokLen": 1
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "range": {
+// CHECK-NEXT:     "begin": {
+// CHECK-NEXT:      "col": 1,
+// CHECK-NEXT:      "tokLen": 6
+// CHECK-NEXT:     },
+// CHECK-NEXT:     "end": {
+// CHECK-NEXT:      "line": 12,
+// CHECK-NEXT:      "col": 1,
+// CHECK-NEXT:      "tokLen": 1
+// CHECK-NEXT:     }
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "name": "S",
+// CHECK-NEXT:    "tagUsed": "struct",
+// CHECK-NEXT:    "completeDefinition": true,
+// CHECK-NEXT:    "definitionData": {
+// CHECK-NEXT:     "canConstDefaultInit": true,
+// CHECK-NEXT:     "canPassInRegisters": true,
+// CHECK-NEXT:     "copyAssign": {
+// CHECK-NEXT:      "hasConstParam": true,
+// CHECK-NEXT:      "implicitHasConstParam": true,
+// CHECK-NEXT:      "needsImplicit": true,
+// CHECK-NEXT:      "trivial": true
+// CHECK-NEXT:     },
+// CHECK-NEXT:     "copyCtor": {
+// CHECK-NEXT:      "hasConstParam": true,
+// CHECK-NEXT:      "implicitHasConstParam": true,
+// CHECK-NEXT:      "needsImplicit": true,
+// CHECK-NEXT:      "simple": true,
+// CHECK-NEXT:      "trivial": true
+// CHECK-NEXT:     },
+// CHECK-NEXT:     "defaultCtor": {
+// CHECK-NEXT:      "defaultedIsConstexpr": true,
+// CHECK-NEXT:      "exists": true,
+// CHECK-NEXT:      "isConstexpr": true,
+// CHECK-NEXT:      "needsImplicit": true,
+// CHECK-NEXT:      "trivial": true
+// CHECK-NEXT:     },
+// CHECK-NEXT:     "dtor": {
+// CHECK-NEXT:      "irrelevant": true,
+// CHECK-NEXT:      "needsImplicit": true,
+// CHECK-NEXT:      "simple": true,
+// CHECK-NEXT:      "trivial": true
+// CHECK-NEXT:     },
+// CHECK-NEXT:     "hasConstexprNonCopyMoveConstructor": true,
+// CHECK-NEXT:     "isAggregate": true,
+// CHECK-NEXT:     "isEmpty": true,
+// CHECK-NEXT:     "isLiteral": true,
+// CHECK-NEXT:     "isPOD": true,
+// CHECK-NEXT:     "isStandardLayout": true,
+// CHECK-NEXT:     "isTrivial": true,
+// CHECK-NEXT:     "isTriviallyCopyable": true,
+// CHECK-NEXT:     "moveAssign": {
+// CHECK-NEXT:      "exists": true,
+// CHECK-NEXT:      "needsImplicit": true,
+// CHECK-NEXT:      "simple": true,
+// CHECK-NEXT:      "trivial": true
+// CHECK-NEXT:     },
+// CHECK-NEXT:     "moveCtor": {
+// CHECK-NEXT:      "exists": true,
+// CHECK-NEXT:      "needsImplicit": true,
+// CHECK-NEXT:      "simple": true,
+// CHECK-NEXT:      "trivial": true
+// CHECK-NEXT:     }
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "inner": [
+// CHECK-NEXT:     {
+// CHECK-NEXT:      "id": "0x{{.*}}",
+// CHECK-NEXT:      "kind": "CXXRecordDecl",
+// CHECK-NEXT:      "loc": {
+// CHECK-NEXT:       "line": 10,
+// CHECK-NEXT:       "col": 8,
+// CHECK-NEXT:       "tokLen": 1
+// CHECK-NEXT:      },
+// CHECK-NEXT:      "range": {
+// CHECK-NEXT:       "begin": {
+// CHECK-NEXT:        "col": 1,
+// CHECK-NEXT:        "tokLen": 6
+// CHECK-NEXT:       },
+// CHECK-NEXT:       "end": {
+// CHECK-NEXT:        "col": 8,
+// CHECK-NEXT:        "tokLen": 1
+// CHECK-NEXT:       }
+// CHECK-NEXT:      },
+// CHECK-NEXT:      "isImplicit": true,
+// CHECK-NEXT:      "name": "S",
+// CHECK-NEXT:      "tagUsed": "struct"
+// CHECK-NEXT:     },
+// CHECK-NEXT:     {
+// CHECK-NEXT:      "id": "0x[[METHOD_ID:.*]]",
+// CHECK-NEXT:      "kind": "CXXMethodDecl",
+// CHECK-NEXT:      "loc": {
+// CHECK-NEXT:       "line": 11,
+// CHECK-NEXT:       "col": 8,
+// CHECK-NEXT:       "tokLen": 6
+// CHECK-NEXT:      },
+// CHECK-NEXT:      "range": {
+// CHECK-NEXT:       "begin": {
+// CHECK-NEXT:        "col": 3,
+// CHECK-NEXT:        "tokLen": 4
+// CHECK-NEXT:       },
+// CHECK-NEXT:       "end": {
+// CHECK-NEXT:        "col": 15,
+// CHECK-NEXT:        "tokLen": 1
+// CHECK-NEXT:       }
+// CHECK-NEXT:      },
+// CHECK-NEXT:      "name": "Method",
+// CHECK-NEXT:      "type": {
+// CHECK-NEXT:       "qualType": "void ()"
+// CHECK-NEXT:      }
+// CHECK-NEXT:     }
+// CHECK-NEXT:    ]
+// CHECK-NEXT:   },
+// CHECK-NEXT:   {
+// CHECK-NEXT:    "id": "0x{{.*}}",
+// CHECK-NEXT:    "kind": "CXXMethodDecl",
+// CHECK-NEXT:    "loc": {
+// CHECK-NEXT:     "line": 13,
+// CHECK-NEXT:     "col": 9,
+// CHECK-NEXT:     "tokLen": 6
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "range": {
+// CHECK-NEXT:     "begin": {
+// CHECK-NEXT:      "col": 1,
+// CHECK-NEXT:      "tokLen": 4
+// CHECK-NEXT:     },
+// CHECK-NEXT:     "end": {
+// CHECK-NEXT:      "col": 19,
+// CHECK-NEXT:      "tokLen": 1
+// CHECK-NEXT:     }
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "parentDeclContextId": "0x[[S_ID]]",
+// CHECK-NEXT:    "previousDecl": "0x[[METHOD_ID]]",
+// CHECK-NEXT:    "name": "Method",
+// CHECK-NEXT:    "type": {
+// CHECK-NEXT:     "qualType": "void ()"
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "inner": [
+// CHECK-NEXT:     {
+// CHECK-NEXT:      "id": "0x{{.*}}",
+// CHECK-NEXT:      "kind": "CompoundStmt",
+// CHECK-NEXT:      "range": {
+// CHECK-NEXT:       "begin": {
+// CHECK-NEXT:        "col": 18,
+// CHECK-NEXT:        "tokLen": 1
+// CHECK-NEXT:       },
+// CHECK-NEXT:       "end": {
+// CHECK-NEXT:        "col": 19,
+// CHECK-NEXT:        "tokLen": 1
+// CHECK-NEXT:       }
+// CHECK-NEXT:      }
+// CHECK-NEXT:     }
+// CHECK-NEXT:    ]
+// CHECK-NEXT:   }
+// CHECK-NEXT:  ]
+// CHECK-NEXT: }
Index: clang/test/AST/ast-dump-decl-json.c
===================================================================
--- clang/test/AST/ast-dump-decl-json.c
+++ clang/test/AST/ast-dump-decl-json.c
@@ -226,7 +226,7 @@
 // CHECK-NEXT:      "tokLen": 1
 // CHECK-NEXT:     }
 // CHECK-NEXT:    },
-// CHECK-NEXT:    "parentDeclContext": "0x{{.*}}",
+// CHECK-NEXT:    "parentDeclContextId": "0x{{.*}}",
 // CHECK-NEXT:    "name": "y",
 // CHECK-NEXT:    "tagUsed": "struct",
 // CHECK-NEXT:    "completeDefinition": true,
Index: clang/test/AST/ast-dump-funcs-json.cpp
===================================================================
--- clang/test/AST/ast-dump-funcs-json.cpp
+++ clang/test/AST/ast-dump-funcs-json.cpp
@@ -426,7 +426,7 @@
 // CHECK-NEXT:    "tokLen": 1
 // CHECK-NEXT:   }
 // CHECK-NEXT:  },
-// CHECK-NEXT:  "parentDeclContext": "0x{{.*}}",
+// CHECK-NEXT:  "parentDeclContextId": "0x{{.*}}",
 // CHECK-NEXT:  "previousDecl": "0x{{.*}}",
 // CHECK-NEXT:  "name": "Test1",
 // CHECK-NEXT:  "type": {
Index: clang/test/AST/ast-dump-template-decls-json.cpp
===================================================================
--- clang/test/AST/ast-dump-template-decls-json.cpp
+++ clang/test/AST/ast-dump-template-decls-json.cpp
@@ -2217,7 +2217,7 @@
 // CHECK-NEXT:      "tokLen": 1
 // CHECK-NEXT:     }
 // CHECK-NEXT:    },
-// CHECK-NEXT:    "parentDeclContext": "0x{{.*}}",
+// CHECK-NEXT:    "parentDeclContextId": "0x{{.*}}",
 // CHECK-NEXT:    "previousDecl": "0x{{.*}}",
 // CHECK-NEXT:    "name": "f",
 // CHECK-NEXT:    "inner": [
@@ -2264,7 +2264,7 @@
 // CHECK-NEXT:        "tokLen": 1
 // CHECK-NEXT:       }
 // CHECK-NEXT:      },
-// CHECK-NEXT:      "parentDeclContext": "0x{{.*}}",
+// CHECK-NEXT:      "parentDeclContextId": "0x{{.*}}",
 // CHECK-NEXT:      "previousDecl": "0x{{.*}}",
 // CHECK-NEXT:      "name": "f",
 // CHECK-NEXT:      "type": {