diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 8f1da78f1e9..bfd261802f4 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -3634,6 +3634,10 @@
         "category": "Message",
         "code": 6359
     },
+    "Project '{0}' is up to date": {
+        "category": "Message",
+        "code": 6360
+    },
 
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",
diff --git a/src/compiler/tsbuild.ts b/src/compiler/tsbuild.ts
index 10ed5280f71..ec9e18899aa 100644
--- a/src/compiler/tsbuild.ts
+++ b/src/compiler/tsbuild.ts
@@ -608,10 +608,11 @@ namespace ts {
             }
         }
 
-        // TODO Accept parsedCommandLine
+        // TODO Accept parsedCommandLine instead?
         function buildSingleProject(proj: string) {
             if (context.options.dry) {
                 reportDiagnostic(createCompilerDiagnostic(Diagnostics.Would_build_project_0, proj));
+                return;
             }
 
             context.verbose(Diagnostics.Building_project_0, proj);
@@ -714,34 +715,47 @@ namespace ts {
             context.projectStatus.setValue(proj.options.configFilePath, { type: UpToDateStatusType.UpToDate, newestDeclarationFileContentChangedTime: priorNewestUpdateTime } as UpToDateStatus);
         }
 
-        function cleanProjects(configFileNames: string[]) {
-            // Get the same graph for cleaning we'd use for building
-            const graph = createDependencyGraph(configFileNames);
+        function getFilesToClean(configFileNames: string[]): string[] | undefined {
+            const resolvedNames: string[] | undefined = resolveProjectNames(configFileNames);
+            if (resolvedNames === undefined) return;
 
-            const fileReport: string[] = [];
+            // Get the same graph for cleaning we'd use for building
+            const graph = createDependencyGraph(resolvedNames);
+
+            const filesToDelete: string[] = [];
             for (const level of graph.buildQueue) {
                 for (const proj of level) {
                     const parsed = configFileCache.parseConfigFile(proj);
                     const outputs = getAllProjectOutputs(parsed);
                     for (const output of outputs) {
                         if (host.fileExists(output)) {
-                            if (context.options.dry) {
-                                fileReport.push(output);
-                            }
-                            else {
-                                host.deleteFile(output);
-                            }
+                            filesToDelete.push(output);
                         }
                     }
                 }
             }
+            return filesToDelete;
+        }
+
+        function cleanProjects(configFileNames: string[]) {
+            const filesToDelete = getFilesToClean(configFileNames);
 
             if (context.options.dry) {
-                reportDiagnostic(createCompilerDiagnostic(Diagnostics.Would_delete_the_following_files_Colon_0, fileReport.map(f => `\r\n * ${f}`).join("")));
+                 reportDiagnostic(createCompilerDiagnostic(Diagnostics.Would_delete_the_following_files_Colon_0, filesToDelete.map(f => `\r\n * ${f}`).join("")));
+            }
+            else {
+                if (!host.deleteFile) {
+                    throw new Error("Host does not support deleting files");
+                }
+
+                for (const output of filesToDelete) {
+                    host.deleteFile(output);
+                }
             }
         }
 
-        function buildProjects(configFileNames: string[]) {
+        // TODO add branding to resolved filenames
+        function resolveProjectNames(configFileNames: string[]): string[] | undefined {
             const resolvedNames: string[] = [];
             for (const name of configFileNames) {
                 let fullPath = resolvePath(host.getCurrentDirectory(), name);
@@ -755,8 +769,14 @@ namespace ts {
                     continue;
                 }
                 reportDiagnostic(createCompilerDiagnostic(Diagnostics.File_0_not_found, fullPath));
-                return;
+                return undefined;
             }
+            return resolvedNames;
+        }
+
+        function buildProjects(configFileNames: string[]) {
+            const resolvedNames: string[] | undefined = resolveProjectNames(configFileNames);
+            if (resolvedNames === undefined) return;
 
             // Establish what needs to be built
             const graph = createDependencyGraph(resolvedNames);
@@ -772,6 +792,10 @@ namespace ts {
 
                 if (status.type === UpToDateStatusType.UpToDate && !context.options.force) {
                     // Up to date, skip
+                    if (options.dry) {
+                        // In a dry build, inform the user of this fact
+                        reportDiagnostic(createCompilerDiagnostic(Diagnostics.Project_0_is_up_to_date));
+                    }
                     continue;
                 }
 
diff --git a/src/harness/fakes.ts b/src/harness/fakes.ts
index f5a2861d385..958629a0988 100644
--- a/src/harness/fakes.ts
+++ b/src/harness/fakes.ts
@@ -51,6 +51,10 @@ namespace fakes {
             this.vfs.writeFileSync(path, writeByteOrderMark ? utils.addUTF8ByteOrderMark(data) : data);
         }
 
+        public deleteFile(path: string) {
+            this.vfs.unlinkSync(path);
+        }
+
         public fileExists(path: string) {
             const stats = this._getStats(path);
             return stats ? stats.isFile() : false;
@@ -248,6 +252,10 @@ namespace fakes {
             return this.sys.useCaseSensitiveFileNames ? fileName : fileName.toLowerCase();
         }
 
+        public deleteFile(fileName: string) {
+            this.sys.deleteFile(fileName);
+        }
+
         public fileExists(fileName: string): boolean {
             return this.sys.fileExists(fileName);
         }
diff --git a/src/harness/unittests/tsbuild.ts b/src/harness/unittests/tsbuild.ts
index e84fa403475..a761e154898 100644
--- a/src/harness/unittests/tsbuild.ts
+++ b/src/harness/unittests/tsbuild.ts
@@ -11,6 +11,9 @@ namespace ts {
     bfs.meta.set("defaultLibLocation", "/lib");
     bfs.makeReadonly();
     tick();
+    const allExpectedOutputs = ["/src/tests/index.js",
+        "/src/core/index.js", "/src/core/index.d.ts",
+        "/src/logic/index.js", "/src/logic/index.d.ts"];
 
     describe("tsbuild - sanity check of clean build of 'sample1' project", () => {
         it("can build the sample project 'sample1' without error", () => {
@@ -23,13 +26,95 @@ namespace ts {
             assertDiagnosticMessages(/*empty*/);
 
             // Check for outputs. Not an exhaustive list
-            const expectedOutputs = ["/src/tests/index.js", "/src/core/index.js", "/src/core/index.d.ts"];
-            for (const output of expectedOutputs) {
+            for (const output of allExpectedOutputs) {
                 assert(fs.existsSync(output), `Expect file ${output} to exist`);
             }
         });
     });
 
+    describe("tsbuild - dry builds", () => {
+        it("doesn't write any files in a dry build", () => {
+            clearDiagnostics();
+            const fs = bfs.shadow();
+            const host = new fakes.CompilerHost(fs);
+            const builder = createSolutionBuilder(host, reportDiagnostic, { dry: true, force: false, verbose: false });
+            fs.chdir("/src/tests");
+            builder.buildProjects(["."]);
+            assertDiagnosticMessages(Diagnostics.Would_build_project_0, Diagnostics.Would_build_project_0, Diagnostics.Would_build_project_0);
+
+            // Check for outputs to not be written. Not an exhaustive list
+            for (const output of allExpectedOutputs) {
+                assert(!fs.existsSync(output), `Expect file ${output} to not exist`);
+            }
+        });
+
+        it("indicates that it would skip builds during a dry build", () => {
+            clearDiagnostics();
+            const fs = bfs.shadow();
+            const host = new fakes.CompilerHost(fs);
+
+            let builder = createSolutionBuilder(host, reportDiagnostic, { dry: false, force: false, verbose: false });
+            fs.chdir("/src/tests");
+            builder.buildProjects(["."]);
+            tick();
+
+            clearDiagnostics();
+            builder = createSolutionBuilder(host, reportDiagnostic, { dry: true, force: false, verbose: false });
+            builder.buildProjects(["."]);
+            assertDiagnosticMessages(Diagnostics.Project_0_is_up_to_date, Diagnostics.Project_0_is_up_to_date, Diagnostics.Project_0_is_up_to_date);
+        });
+    });
+
+    describe("tsbuild - clean builds", () => {
+        it("removes all files it built", () => {
+            clearDiagnostics();
+            const fs = bfs.shadow();
+            const host = new fakes.CompilerHost(fs);
+
+            const builder = createSolutionBuilder(host, reportDiagnostic, { dry: false, force: false, verbose: false });
+            fs.chdir("/src/tests");
+            builder.buildProjects(["."]);
+            // Verify they exist
+            for (const output of allExpectedOutputs) {
+                assert(fs.existsSync(output), `Expect file ${output} to exist`);
+            }
+            builder.cleanProjects(["."]);
+            // Verify they are gone
+            for (const output of allExpectedOutputs) {
+                assert(!fs.existsSync(output), `Expect file ${output} to not exist`);
+            }
+            // Subsequent clean shouldn't throw / etc
+            builder.cleanProjects(["."]);
+        });
+    });
+
+    describe("tsbuild - force builds", () => {
+        it("always builds under --force", () => {
+            const fs = bfs.shadow();
+            const host = new fakes.CompilerHost(fs);
+
+            const builder = createSolutionBuilder(host, reportDiagnostic, { dry: false, force: true, verbose: false });
+            fs.chdir("/src/tests");
+            builder.buildProjects(["."]);
+            let currentTime = time();
+            checkOutputTimestamps(currentTime);
+
+            tick();
+            Debug.assert(time() !== currentTime, "Time moves on");
+            currentTime = time();
+            builder.buildProjects(["."]);
+            checkOutputTimestamps(currentTime);
+
+            function checkOutputTimestamps(expected: number) {
+                // Check timestamps
+                for (const output of allExpectedOutputs) {
+                    const actual = fs.statSync(output).mtimeMs;
+                    assert(actual === expected, `File ${output} has timestamp ${actual}, expected ${expected}`);
+                }
+            }
+        });
+    });
+
     describe("tsbuild - can detect when and what to rebuild", () => {
         const fs = bfs.shadow();
         const host = new fakes.CompilerHost(fs);
@@ -38,6 +123,7 @@ namespace ts {
         fs.chdir("/src/tests");
 
         it("Builds the project", () => {
+            clearDiagnostics();
             builder.resetBuildContext();
             builder.buildProjects(["."]);
             assertDiagnosticMessages(Diagnostics.Sorted_list_of_input_projects_Colon_0,