diff --git a/modules/@angular/router/src/create_url_tree.ts b/modules/@angular/router/src/create_url_tree.ts
index 6d9cb24b90..d2794d07e5 100644
--- a/modules/@angular/router/src/create_url_tree.ts
+++ b/modules/@angular/router/src/create_url_tree.ts
@@ -42,13 +42,11 @@ function validateCommands(n: NormalizedNavigationCommands): void {
 function tree(
     oldSegment: UrlSegment, newSegment: UrlSegment, urlTree: UrlTree, queryParams: Params,
     fragment: string): UrlTree {
-  const q = queryParams ? stringify(queryParams) : urlTree.queryParams;
-  const f = fragment ? fragment : urlTree.fragment;
-
   if (urlTree.root === oldSegment) {
-    return new UrlTree(newSegment, q, f);
+    return new UrlTree(newSegment, stringify(queryParams), fragment);
   } else {
-    return new UrlTree(replaceSegment(urlTree.root, oldSegment, newSegment), q, f);
+    return new UrlTree(
+        replaceSegment(urlTree.root, oldSegment, newSegment), stringify(queryParams), fragment);
   }
 }
 
diff --git a/modules/@angular/router/src/directives/router_link.ts b/modules/@angular/router/src/directives/router_link.ts
index 904e44f0ca..ad26a4f17d 100644
--- a/modules/@angular/router/src/directives/router_link.ts
+++ b/modules/@angular/router/src/directives/router_link.ts
@@ -51,9 +51,15 @@ import {UrlTree} from '../url_tree';
  * <a [routerLink]="['/user/bob']" [queryParams]="{debug: true}" fragment="education">link to user
  component</a>
  * ```
- *
  * RouterLink will use these to generate this link: `/user/bob#education?debug=true`.
  *
+ * You can also tell the directive to preserve the current query params and fragment:
+ *
+ * ```
+ * <a [routerLink]="['/user/bob']" preserveQueryParams preserveFragment>link to user
+ component</a>
+ * ```
+ *
  * @stable
  */
 @Directive({selector: ':not(a)[routerLink]'})
@@ -61,6 +67,8 @@ export class RouterLink {
   private commands: any[] = [];
   @Input() queryParams: {[k: string]: any};
   @Input() fragment: string;
+  @Input() preserveQueryParams: boolean;
+  @Input() preserveFragment: boolean;
 
   constructor(
       private router: Router, private route: ActivatedRoute,
@@ -85,9 +93,13 @@ export class RouterLink {
   }
 
   get urlTree(): UrlTree {
-    return this.router.createUrlTree(
-        this.commands,
-        {relativeTo: this.route, queryParams: this.queryParams, fragment: this.fragment});
+    return this.router.createUrlTree(this.commands, {
+      relativeTo: this.route,
+      queryParams: this.queryParams,
+      fragment: this.fragment,
+      preserveQueryParams: toBool(this.preserveQueryParams),
+      preserveFragment: toBool(this.preserveFragment)
+    });
   }
 }
 
@@ -101,6 +113,9 @@ export class RouterLinkWithHref implements OnChanges, OnDestroy {
   private commands: any[] = [];
   @Input() queryParams: {[k: string]: any};
   @Input() fragment: string;
+  @Input() routerLinkOptions: {preserveQueryParams: boolean, preserveFragment: boolean};
+  @Input() preserveQueryParams: boolean;
+  @Input() preserveFragment: boolean;
   private subscription: Subscription;
 
   // the url displayed on the anchor element.
@@ -148,12 +163,21 @@ export class RouterLinkWithHref implements OnChanges, OnDestroy {
   }
 
   private updateTargetUrlAndHref(): void {
-    this.urlTree = this.router.createUrlTree(
-        this.commands,
-        {relativeTo: this.route, queryParams: this.queryParams, fragment: this.fragment});
+    this.urlTree = this.router.createUrlTree(this.commands, {
+      relativeTo: this.route,
+      queryParams: this.queryParams,
+      fragment: this.fragment,
+      preserveQueryParams: toBool(this.preserveQueryParams),
+      preserveFragment: toBool(this.preserveFragment)
+    });
 
     if (this.urlTree) {
       this.href = this.locationStrategy.prepareExternalUrl(this.router.serializeUrl(this.urlTree));
     }
   }
 }
+
+function toBool(s?: any): boolean {
+  if (s === '') return true;
+  return !!s;
+}
\ No newline at end of file
diff --git a/modules/@angular/router/src/router.ts b/modules/@angular/router/src/router.ts
index 913ad39a1a..d00f0ddf40 100644
--- a/modules/@angular/router/src/router.ts
+++ b/modules/@angular/router/src/router.ts
@@ -45,6 +45,8 @@ export interface NavigationExtras {
   relativeTo?: ActivatedRoute;
   queryParams?: Params;
   fragment?: string;
+  preserveQueryParams?: boolean;
+  preserveFragment?: boolean;
 }
 
 /**
@@ -227,10 +229,13 @@ export class Router {
    * router.createUrlTree(['../../team/44/user/22'], {relativeTo: route});
    * ```
    */
-  createUrlTree(commands: any[], {relativeTo, queryParams, fragment}: NavigationExtras = {}):
-      UrlTree {
+  createUrlTree(
+      commands: any[], {relativeTo, queryParams, fragment, preserveQueryParams,
+                        preserveFragment}: NavigationExtras = {}): UrlTree {
     const a = relativeTo ? relativeTo : this.routerState.root;
-    return createUrlTree(a, this.currentUrlTree, commands, queryParams, fragment);
+    const q = preserveQueryParams ? this.currentUrlTree.queryParams : queryParams;
+    const f = preserveFragment ? this.currentUrlTree.fragment : fragment;
+    return createUrlTree(a, this.currentUrlTree, commands, q, f);
   }
 
   /**
diff --git a/modules/@angular/router/src/url_tree.ts b/modules/@angular/router/src/url_tree.ts
index 69759449c8..c7db4b6d71 100644
--- a/modules/@angular/router/src/url_tree.ts
+++ b/modules/@angular/router/src/url_tree.ts
@@ -183,7 +183,9 @@ export class DefaultUrlSerializer implements UrlSerializer {
   serialize(tree: UrlTree): string {
     const segment = `/${serializeSegment(tree.root, true)}`;
     const query = serializeQueryParams(tree.queryParams);
-    const fragment = tree.fragment !== null ? `#${encodeURIComponent(tree.fragment)}` : '';
+    const fragment = tree.fragment !== null && tree.fragment !== undefined ?
+        `#${encodeURIComponent(tree.fragment)}` :
+        '';
     return `${segment}${query}${fragment}`;
   }
 }
diff --git a/modules/@angular/router/test/create_url_tree.spec.ts b/modules/@angular/router/test/create_url_tree.spec.ts
index 9189e72c42..821d440af4 100644
--- a/modules/@angular/router/test/create_url_tree.spec.ts
+++ b/modules/@angular/router/test/create_url_tree.spec.ts
@@ -182,23 +182,11 @@ describe('createUrlTree', () => {
     expect(t.queryParams).toEqual({a: '1'});
   });
 
-  it('should reuse old query params when given undefined', () => {
-    const p = serializer.parse('/?a=1');
-    const t = createRoot(p, [], undefined);
-    expect(t.queryParams).toEqual({a: '1'});
-  });
-
   it('should set fragment', () => {
     const p = serializer.parse('/');
     const t = createRoot(p, [], {}, 'fragment');
     expect(t.fragment).toEqual('fragment');
   });
-
-  it('should reused old fragment when given undefined', () => {
-    const p = serializer.parse('/#fragment');
-    const t = createRoot(p, [], undefined, undefined);
-    expect(t.fragment).toEqual('fragment');
-  });
 });
 
 
diff --git a/modules/@angular/router/test/router.spec.ts b/modules/@angular/router/test/router.spec.ts
index fd0c4ea628..9c667d41a7 100644
--- a/modules/@angular/router/test/router.spec.ts
+++ b/modules/@angular/router/test/router.spec.ts
@@ -594,10 +594,9 @@ describe('Integration', () => {
              expect(fixture.debugElement.nativeElement).toHaveText('team 33 [ simple, right:  ]');
            })));
 
-    it('should update hrefs when query params change',
+    it('should not preserve query params and fragment by default',
        fakeAsync(
            inject([Router, TestComponentBuilder], (router: Router, tcb: TestComponentBuilder) => {
-
              @Component({
                selector: 'someRoot',
                template: `<router-outlet></router-outlet><a routerLink="/home">Link</a>`,
@@ -612,15 +611,42 @@ describe('Integration', () => {
 
              const native = fixture.debugElement.nativeElement.querySelector('a');
 
-             router.navigateByUrl('/home?q=123');
+             router.navigateByUrl('/home?q=123#fragment');
              advance(fixture);
-             expect(native.getAttribute('href')).toEqual('/home?q=123');
-
-             router.navigateByUrl('/home?q=456');
-             advance(fixture);
-             expect(native.getAttribute('href')).toEqual('/home?q=456');
+             expect(native.getAttribute('href')).toEqual('/home');
            })));
 
+    it('should update hrefs when query params or fragment change',
+       fakeAsync(inject([Router, TestComponentBuilder], (router: Router, tcb: TestComponentBuilder) => {
+
+         @Component({
+           selector: 'someRoot',
+           template:
+               `<router-outlet></router-outlet><a routerLink="/home" preserveQueryParams preserveFragment>Link</a>`,
+           directives: ROUTER_DIRECTIVES
+         })
+         class RootCmpWithLink {
+         }
+
+         const fixture = createRoot(tcb, router, RootCmpWithLink);
+
+         router.resetConfig([{path: 'home', component: SimpleCmp}]);
+
+         const native = fixture.debugElement.nativeElement.querySelector('a');
+
+         router.navigateByUrl('/home?q=123');
+         advance(fixture);
+         expect(native.getAttribute('href')).toEqual('/home?q=123');
+
+         router.navigateByUrl('/home?q=456');
+         advance(fixture);
+         expect(native.getAttribute('href')).toEqual('/home?q=456');
+
+         router.navigateByUrl('/home?q=456#1');
+         advance(fixture);
+         expect(native.getAttribute('href')).toEqual('/home?q=456#1');
+       })));
+
     it('should support using links on non-a tags',
        fakeAsync(
            inject([Router, TestComponentBuilder], (router: Router, tcb: TestComponentBuilder) => {