diff --git a/bin/spark-class b/bin/spark-class
index 5d964ba96abd8..e710e388be1bc 100755
--- a/bin/spark-class
+++ b/bin/spark-class
@@ -35,42 +35,27 @@ else
   fi
 fi
 
-# Find assembly jar
-SPARK_ASSEMBLY_JAR=
+# Find Spark jars.
+# TODO: change the directory name when Spark jars move from "lib".
 if [ -f "${SPARK_HOME}/RELEASE" ]; then
-  ASSEMBLY_DIR="${SPARK_HOME}/lib"
+  SPARK_JARS_DIR="${SPARK_HOME}/lib"
 else
-  ASSEMBLY_DIR="${SPARK_HOME}/assembly/target/scala-$SPARK_SCALA_VERSION"
+  SPARK_JARS_DIR="${SPARK_HOME}/assembly/target/scala-$SPARK_SCALA_VERSION"
 fi
 
-GREP_OPTIONS=
-num_jars="$(ls -1 "$ASSEMBLY_DIR" | grep "^spark-assembly.*hadoop.*\.jar$" | wc -l)"
-if [ "$num_jars" -eq "0" -a -z "$SPARK_ASSEMBLY_JAR" -a "$SPARK_PREPEND_CLASSES" != "1" ]; then
-  echo "Failed to find Spark assembly in $ASSEMBLY_DIR." 1>&2
+if [ ! -d "$SPARK_JARS_DIR" ]; then
+  echo "Failed to find Spark jars directory ($SPARK_JARS_DIR)." 1>&2
   echo "You need to build Spark before running this program." 1>&2
   exit 1
 fi
-if [ -d "$ASSEMBLY_DIR" ]; then
-  ASSEMBLY_JARS="$(ls -1 "$ASSEMBLY_DIR" | grep "^spark-assembly.*hadoop.*\.jar$" || true)"
-  if [ "$num_jars" -gt "1" ]; then
-    echo "Found multiple Spark assembly jars in $ASSEMBLY_DIR:" 1>&2
-    echo "$ASSEMBLY_JARS" 1>&2
-    echo "Please remove all but one jar." 1>&2
-    exit 1
-  fi
-fi
 
-SPARK_ASSEMBLY_JAR="${ASSEMBLY_DIR}/${ASSEMBLY_JARS}"
-
-LAUNCH_CLASSPATH="$SPARK_ASSEMBLY_JAR"
+LAUNCH_CLASSPATH="$SPARK_JARS_DIR/*"
 
 # Add the launcher build dir to the classpath if requested.
 if [ -n "$SPARK_PREPEND_CLASSES" ]; then
   LAUNCH_CLASSPATH="${SPARK_HOME}/launcher/target/scala-$SPARK_SCALA_VERSION/classes:$LAUNCH_CLASSPATH"
 fi
 
-export _SPARK_ASSEMBLY="$SPARK_ASSEMBLY_JAR"
-
 # For tests
 if [[ -n "$SPARK_TESTING" ]]; then
   unset YARN_CONF_DIR
diff --git a/bin/spark-class2.cmd b/bin/spark-class2.cmd
index c4fadb822323d..565b87c102b19 100644
--- a/bin/spark-class2.cmd
+++ b/bin/spark-class2.cmd
@@ -28,33 +28,27 @@ if "x%1"=="x" (
   exit /b 1
 )
 
-rem Find assembly jar
-set SPARK_ASSEMBLY_JAR=0
-
+rem Find Spark jars.
+rem TODO: change the directory name when Spark jars move from "lib".
 if exist "%SPARK_HOME%\RELEASE" (
-  set ASSEMBLY_DIR="%SPARK_HOME%\lib"
+  set SPARK_JARS_DIR="%SPARK_HOME%\lib"
 ) else (
-  set ASSEMBLY_DIR="%SPARK_HOME%\assembly\target\scala-%SPARK_SCALA_VERSION%"
+  set SPARK_JARS_DIR="%SPARK_HOME%\assembly\target\scala-%SPARK_SCALA_VERSION%"
 )
 
-for %%d in (%ASSEMBLY_DIR%\spark-assembly*hadoop*.jar) do (
-  set SPARK_ASSEMBLY_JAR=%%d
-)
-if "%SPARK_ASSEMBLY_JAR%"=="0" (
+if not exist "%SPARK_JARS_DIR%"\ (
   echo Failed to find Spark assembly JAR.
   echo You need to build Spark before running this program.
   exit /b 1
 )
 
-set LAUNCH_CLASSPATH=%SPARK_ASSEMBLY_JAR%
+set LAUNCH_CLASSPATH=%SPARK_JARS_DIR%\*
 
 rem Add the launcher build dir to the classpath if requested.
 if not "x%SPARK_PREPEND_CLASSES%"=="x" (
   set LAUNCH_CLASSPATH="%SPARK_HOME%\launcher\target\scala-%SPARK_SCALA_VERSION%\classes;%LAUNCH_CLASSPATH%"
 )
 
-set _SPARK_ASSEMBLY=%SPARK_ASSEMBLY_JAR%
-
 rem Figure out where java is.
 set RUNNER=java
 if not "x%JAVA_HOME%"=="x" set RUNNER=%JAVA_HOME%\bin\java
diff --git a/launcher/src/main/java/org/apache/spark/launcher/AbstractCommandBuilder.java b/launcher/src/main/java/org/apache/spark/launcher/AbstractCommandBuilder.java
index 20387e0f1068d..f6c7e07654ee9 100644
--- a/launcher/src/main/java/org/apache/spark/launcher/AbstractCommandBuilder.java
+++ b/launcher/src/main/java/org/apache/spark/launcher/AbstractCommandBuilder.java
@@ -19,7 +19,6 @@
 
 import java.io.BufferedReader;
 import java.io.File;
-import java.io.FileFilter;
 import java.io.FileInputStream;
 import java.io.InputStreamReader;
 import java.io.IOException;
@@ -172,21 +171,13 @@ List<String> buildClassPath(String appClassPath) throws IOException {
       addToClassPath(cp, String.format("%s/core/target/jars/*", sparkHome));
     }
 
-    // We can't rely on the ENV_SPARK_ASSEMBLY variable to be set. Certain situations, such as
-    // when running unit tests, or user code that embeds Spark and creates a SparkContext
-    // with a local or local-cluster master, will cause this code to be called from an
-    // environment where that env variable is not guaranteed to exist.
-    //
-    // For the testing case, we rely on the test code to set and propagate the test classpath
-    // appropriately.
-    //
-    // For the user code case, we fall back to looking for the Spark assembly under SPARK_HOME.
-    // That duplicates some of the code in the shell scripts that look for the assembly, though.
-    String assembly = getenv(ENV_SPARK_ASSEMBLY);
-    if (assembly == null && !isTesting) {
-      assembly = findAssembly();
+    // Add Spark jars to the classpath. For the testing case, we rely on the test code to set and
+    // propagate the test classpath appropriately. For normal invocation, look for the jars
+    // directory under SPARK_HOME.
+    String jarsDir = findJarsDir(!isTesting);
+    if (jarsDir != null) {
+      addToClassPath(cp, join(File.separator, jarsDir, "*"));
     }
-    addToClassPath(cp, assembly);
 
     // Datanucleus jars must be included on the classpath. Datanucleus jars do not work if only
     // included in the uber jar as plugin.xml metadata is lost. Both sbt and maven will populate
@@ -320,28 +311,25 @@ private Properties loadPropertiesFile() throws IOException {
     return props;
   }
 
-  private String findAssembly() {
+  private String findJarsDir(boolean failIfNotFound) {
+    // TODO: change to the correct directory once the assembly build is changed.
     String sparkHome = getSparkHome();
     File libdir;
     if (new File(sparkHome, "RELEASE").isFile()) {
       libdir = new File(sparkHome, "lib");
-      checkState(libdir.isDirectory(), "Library directory '%s' does not exist.",
-          libdir.getAbsolutePath());
+      checkState(!failIfNotFound || libdir.isDirectory(),
+        "Library directory '%s' does not exist.",
+        libdir.getAbsolutePath());
     } else {
       libdir = new File(sparkHome, String.format("assembly/target/scala-%s", getScalaVersion()));
-    }
-
-    final Pattern re = Pattern.compile("spark-assembly.*hadoop.*\\.jar");
-    FileFilter filter = new FileFilter() {
-      @Override
-      public boolean accept(File file) {
-        return file.isFile() && re.matcher(file.getName()).matches();
+      if (!libdir.isDirectory()) {
+        checkState(!failIfNotFound,
+          "Library directory '%s' does not exist; make sure Spark is built.",
+          libdir.getAbsolutePath());
+        libdir = null;
       }
-    };
-    File[] assemblies = libdir.listFiles(filter);
-    checkState(assemblies != null && assemblies.length > 0, "No assemblies found in '%s'.", libdir);
-    checkState(assemblies.length == 1, "Multiple assemblies found in '%s'.", libdir);
-    return assemblies[0].getAbsolutePath();
+    }
+    return libdir != null ? libdir.getAbsolutePath() : null;
   }
 
   private String getConfDir() {
diff --git a/launcher/src/main/java/org/apache/spark/launcher/CommandBuilderUtils.java b/launcher/src/main/java/org/apache/spark/launcher/CommandBuilderUtils.java
index 7942d7372faff..37afafea28fdc 100644
--- a/launcher/src/main/java/org/apache/spark/launcher/CommandBuilderUtils.java
+++ b/launcher/src/main/java/org/apache/spark/launcher/CommandBuilderUtils.java
@@ -30,7 +30,6 @@ class CommandBuilderUtils {
   static final String DEFAULT_MEM = "1g";
   static final String DEFAULT_PROPERTIES_FILE = "spark-defaults.conf";
   static final String ENV_SPARK_HOME = "SPARK_HOME";
-  static final String ENV_SPARK_ASSEMBLY = "_SPARK_ASSEMBLY";
 
   /** The set of known JVM vendors. */
   static enum JavaVendor {
diff --git a/launcher/src/test/java/org/apache/spark/launcher/SparkSubmitCommandBuilderSuite.java b/launcher/src/test/java/org/apache/spark/launcher/SparkSubmitCommandBuilderSuite.java
index a85afb58b9c98..00f967122bd70 100644
--- a/launcher/src/test/java/org/apache/spark/launcher/SparkSubmitCommandBuilderSuite.java
+++ b/launcher/src/test/java/org/apache/spark/launcher/SparkSubmitCommandBuilderSuite.java
@@ -282,7 +282,6 @@ private boolean findInStringList(String list, String sep, String needle) {
   private SparkSubmitCommandBuilder newCommandBuilder(List<String> args) {
     SparkSubmitCommandBuilder builder = new SparkSubmitCommandBuilder(args);
     builder.childEnv.put(CommandBuilderUtils.ENV_SPARK_HOME, System.getProperty("spark.test.home"));
-    builder.childEnv.put(CommandBuilderUtils.ENV_SPARK_ASSEMBLY, "dummy");
     return builder;
   }