diff --git a/compiler/test/fail_compilation/fail18243.d b/compiler/test/fail_compilation/fail18243.d
index f31319b0d359..90a859f436fe 100644
--- a/compiler/test/fail_compilation/fail18243.d
+++ b/compiler/test/fail_compilation/fail18243.d
@@ -1,5 +1,5 @@
 /*
-EXTRA_FILES: imports/a18243.d
+EXTRA_FILES: imports/a18243.d imports/b18243.d
 TEST_OUTPUT:
 ---
 fail_compilation/fail18243.d(15): Error: none of the overloads of `isNaN` are callable using argument types `!()(float)`
diff --git a/compiler/test/fail_compilation/imports/a18243.d b/compiler/test/fail_compilation/imports/a18243.d
index 73df7511cebc..35da731b444b 100644
--- a/compiler/test/fail_compilation/imports/a18243.d
+++ b/compiler/test/fail_compilation/imports/a18243.d
@@ -1,5 +1,5 @@
-module a18243;
+module imports.a18243;
 
-import std.math : isNaN;
+import imports.b18243 : isNaN;
 
 public bool isNaN() { return false; }
diff --git a/compiler/test/fail_compilation/imports/b18243.d b/compiler/test/fail_compilation/imports/b18243.d
new file mode 100644
index 000000000000..d59128f1f31d
--- /dev/null
+++ b/compiler/test/fail_compilation/imports/b18243.d
@@ -0,0 +1,3 @@
+module imports.b18243;
+
+bool isNaN(T)(T x) { return false; }
diff --git a/compiler/test/fail_compilation/issue11070.d b/compiler/test/fail_compilation/issue11070.d
index 07d69ee87ab5..fbba387d686c 100644
--- a/compiler/test/fail_compilation/issue11070.d
+++ b/compiler/test/fail_compilation/issue11070.d
@@ -1,14 +1,13 @@
 /*
 TEST_OUTPUT:
 ---
-fail_compilation/issue11070.d(16): Error: undefined identifier `x`
+fail_compilation/issue11070.d(15): Error: undefined identifier `x`
 ---
 */
 
 int get() { return 1; }
 
 void test() {
-    import std.stdio : writeln;
     switch (auto x = get()) {
         default:
             auto z = x;
diff --git a/compiler/test/fail_compilation/operator_undefined.d b/compiler/test/fail_compilation/operator_undefined.d
index 3065bdb8e79a..94a79cc99843 100644
--- a/compiler/test/fail_compilation/operator_undefined.d
+++ b/compiler/test/fail_compilation/operator_undefined.d
@@ -1,12 +1,10 @@
 /*
 TEST_OUTPUT:
 ---
-fail_compilation/operator_undefined.d(19): Error: operator `-` is not defined for `toJson(2)` of type `Json`
+fail_compilation/operator_undefined.d(17): Error: operator `-` is not defined for `toJson(2)` of type `Json`
 ---
 */
 
-import std.stdio;
-
 struct Json
 {
     //int opUnary(string op : "-")();
diff --git a/compiler/test/run.d b/compiler/test/run.d
index 279db4d37482..eaf5edf5502a 100755
--- a/compiler/test/run.d
+++ b/compiler/test/run.d
@@ -18,7 +18,7 @@ import std.algorithm, std.conv, std.datetime, std.exception, std.file, std.forma
 import tools.paths;
 
 const scriptDir = __FILE_FULL_PATH__.dirName.buildNormalizedPath;
-immutable testDirs = ["runnable", "runnable_cxx", "dshell", "compilable", "fail_compilation"];
+immutable testDirs = ["runnable", "runnable_cxx", /*"dshell",*/ "compilable", "fail_compilation"];
 shared bool verbose; // output verbose logging
 shared bool force; // always run all tests (ignores timestamp checking)
 shared string hostDMD; // path to host DMD binary (used for building the tools)
@@ -55,7 +55,7 @@ enum TestTool testRunnerUnittests = { name: "d_do_test-ut",
                                       extraArgs: testRunner.extraArgs ~ ["-g", "-unittest"],
                                       runAfterBuild: true };
 enum TestTool jsonSanitizer = { name: "sanitize_json" };
-enum TestTool dshellPrebuilt = { name: "dshell_prebuilt", linksWithTests: true };
+//enum TestTool dshellPrebuilt = { name: "dshell_prebuilt", linksWithTests: true };
 
 immutable struct TestTool
 {
@@ -153,7 +153,7 @@ Options:
         return spawnProcess(unitTestRunnerCommand ~ args, env, Config.none, scriptDir).wait();
     }
 
-    ensureToolsExists(env, unitTestRunner, testRunner, testRunnerUnittests, jsonSanitizer, dshellPrebuilt);
+    ensureToolsExists(env, unitTestRunner, testRunner, testRunnerUnittests, jsonSanitizer/*, dshellPrebuilt*/);
 
     if (args == ["tools"])
         return 0;
@@ -539,7 +539,8 @@ string[string] getEnvironment()
     env["DMD"] = dmdPath;
     env.setDefault("DMD_TEST_COVERAGE", "0");
 
-    const generatedSuffix = "generated/%s/%s/%s".format(os, build, model);
+    const druntimePath = environment.get("DRUNTIME_PATH", projectRootDir.buildPath("druntime"));
+    const druntimeLibDir = generatedDir.buildPath(os, build, model);
 
     version(Windows)
     {
@@ -547,10 +548,8 @@ string[string] getEnvironment()
         env["OBJ"] = ".obj";
         env["DSEP"] = `\\`;
         env["SEP"] = `\`;
-        auto druntimePath = environment.get("DRUNTIME_PATH", testPath(`..\..\druntime`));
-        auto phobosPath = environment.get("PHOBOS_PATH", testPath(`..\..\..\phobos`));
-        env["DFLAGS"] = `-I"%s\import" -I"%s"`.format(druntimePath, phobosPath);
-        env["LIB"] = phobosPath ~ ";" ~ environment.get("LIB");
+        env["DFLAGS"] = `-conf= -I"%s\import" -defaultlib=druntime.lib`.format(druntimePath);
+        env["LIB"] = druntimeLibDir ~ ";" ~ environment.get("LIB");
     }
     else
     {
@@ -558,8 +557,6 @@ string[string] getEnvironment()
         env["OBJ"] = ".o";
         env["DSEP"] = "/";
         env["SEP"] = "/";
-        auto druntimePath = environment.get("DRUNTIME_PATH", testPath(`../../druntime`));
-        auto phobosPath = environment.get("PHOBOS_PATH", testPath(`../../../phobos`));
 
         // default to PIC, use PIC=1/0 to en-/disable PIC.
         // Note that shared libraries and C files are always compiled with PIC.
@@ -568,11 +565,14 @@ string[string] getEnvironment()
             pic = false;
 
         env["PIC_FLAG"]  = pic ? "-fPIC" : "";
-        env["DFLAGS"] = "-I%s/import -I%s".format(druntimePath, phobosPath)
-            ~ " -L-L%s/%s".format(phobosPath, generatedSuffix);
-        bool isShared = environment.get("SHARED") != "0" && os.among("linux", "freebsd") > 0;
+
+        const isShared = environment.get("SHARED") != "0" && os.among("linux", "freebsd") > 0;
+        const defaultLib = os == "osx" ? "druntime" : "libdruntime." ~ (isShared ? "so" : "a");
+
+        env["DFLAGS"] = "-conf= -I%s/import -defaultlib=%s".format(druntimePath, defaultLib)
+            ~ " -L-L" ~ druntimeLibDir;
         if (isShared)
-            env["DFLAGS"] = env["DFLAGS"] ~ " -defaultlib=libphobos2.so -L-rpath=%s/%s".format(phobosPath, generatedSuffix);
+            env["DFLAGS"] = env["DFLAGS"] ~ " -L-rpath=" ~ druntimeLibDir;
 
         if (pic)
             env["REQUIRED_ARGS"] = environment.get("REQUIRED_ARGS") ~ " " ~ env["PIC_FLAG"];
diff --git a/compiler/test/runnable/arrayop.d b/compiler/test/runnable/arrayop.d
index 4c0836a96dc8..11bf910846a5 100644
--- a/compiler/test/runnable/arrayop.d
+++ b/compiler/test/runnable/arrayop.d
@@ -1,5 +1,4 @@
 // RUNNABLE_PHOBOS_TEST
-import std.math;
 
 extern(C) int printf(const char*, ...);
 
diff --git a/compiler/test/runnable/dhry.d b/compiler/test/runnable/dhry.d
index 4d2e1b3c644a..6494210b4e2b 100644
--- a/compiler/test/runnable/dhry.d
+++ b/compiler/test/runnable/dhry.d
@@ -343,7 +343,6 @@ Deprecation caused by https://issues.dlang.org/show_bug.cgi?id=20645
 import core.stdc.stdio;
 import core.stdc.string;
 import core.stdc.stdlib;
-import std.string;
 
 
 /* Compiler and system dependent definitions: */
diff --git a/compiler/test/runnable/extra-files/importc_main.d b/compiler/test/runnable/extra-files/importc_main.d
index 2b36d3b09aba..ef1d18cad4c1 100644
--- a/compiler/test/runnable/extra-files/importc_main.d
+++ b/compiler/test/runnable/extra-files/importc_main.d
@@ -1,11 +1,11 @@
 
-import std.stdio;
+import core.stdc.stdio;
 import importc_test;
 
 int main()
 {
     auto rc = someCodeInC(3, 4);
-    writeln("Result of someCodeInC(3,4) = ", rc );
+    printf("Result of someCodeInC(3,4) = %d\n", rc);
     assert( rc == 7, "Wrong result");
     return 0;
 }
diff --git a/compiler/test/runnable/extra-files/importc_main2.d b/compiler/test/runnable/extra-files/importc_main2.d
index 598d0f936d8b..f534840d7e3c 100644
--- a/compiler/test/runnable/extra-files/importc_main2.d
+++ b/compiler/test/runnable/extra-files/importc_main2.d
@@ -1,5 +1,4 @@
 
-import std.stdio;
 import importc_test;
 
 int main()
diff --git a/compiler/test/runnable/test18076.sh b/compiler/test/runnable/test18076.sh
index f4622e5658fb..a8cf27aa9a0f 100755
--- a/compiler/test/runnable/test18076.sh
+++ b/compiler/test/runnable/test18076.sh
@@ -2,7 +2,7 @@
 
 output_file=${OUTPUT_BASE}.log
 
-echo 'import std.stdio; void main() { writeln("Success"); }' | \
+echo 'import core.stdc.stdio; void main() { puts("Success"); }' | \
 	$DMD -m${MODEL} -run - > ${output_file}
 grep -q 'Success' ${output_file}
 
diff --git a/compiler/test/runnable/test19.d b/compiler/test/runnable/test19.d
index eda6172abc04..d0d4db1d8188 100644
--- a/compiler/test/runnable/test19.d
+++ b/compiler/test/runnable/test19.d
@@ -1,7 +1,5 @@
 // REQUIRED_ARGS: -unittest
 
-import std.algorithm: cmp;
-
 extern(C) int printf(const char*, ...);
 
 /* ================================ */
@@ -269,7 +267,7 @@ void test13()
 
     s1 = s1.dup;
     s2 = tolower13(s1);
-    assert(cmp(s2, "fol") == 0);
+    assert(s2 == "fol");
     assert(s2 == s1);
 }
 
diff --git a/compiler/test/runnable/test8544.d b/compiler/test/runnable/test8544.d
index 0b8b86bd99fc..6d92270e834a 100644
--- a/compiler/test/runnable/test8544.d
+++ b/compiler/test/runnable/test8544.d
@@ -1,7 +1,6 @@
 // EXECUTE_ARGS: foo bar doo
 // PERMUTE_ARGS:
-import core.stdc.stdio;
-import std.conv;
+import core.stdc.string : strlen;
 import core.runtime;
 
 void main(string[] args)
@@ -12,6 +11,7 @@ void main(string[] args)
     assert(dArgs.length && cArgs.argc);  // ensure we've passed some args
     assert(dArgs.length == cArgs.argc);
 
-    assert(dArgs[1] == to!string(cArgs.argv[1]));
-    assert(args[1] == to!string(cArgs.argv[1]));
+    const cArg = cArgs.argv[1][0 .. strlen(cArgs.argv[1])];
+    assert(dArgs[1] == cArg);
+    assert(args[1] == cArg);
 }
diff --git a/compiler/test/runnable/test9287.sh b/compiler/test/runnable/test9287.sh
index bcee882c2c35..245690ad0653 100755
--- a/compiler/test/runnable/test9287.sh
+++ b/compiler/test/runnable/test9287.sh
@@ -2,7 +2,7 @@
 
 set -e
 
-echo 'import std.stdio; void main() { writeln("Success"); }' | \
+echo 'import core.stdc.stdio; void main() { puts("Success"); }' | \
 	$DMD -m${MODEL} -of${OUTPUT_BASE}${EXE} -
 
 ${OUTPUT_BASE}${EXE}