diff --git a/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/orm/jpa/JpaBaseConfiguration.java b/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/orm/jpa/JpaBaseConfiguration.java
index d73aa5f696e..f5127fbae73 100644
--- a/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/orm/jpa/JpaBaseConfiguration.java
+++ b/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/orm/jpa/JpaBaseConfiguration.java
@@ -34,6 +34,7 @@ import org.springframework.context.EnvironmentAware;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.env.Environment;
+import org.springframework.orm.jpa.EntityManagerFactoryInfo;
 import org.springframework.orm.jpa.JpaTransactionManager;
 import org.springframework.orm.jpa.JpaVendorAdapter;
 import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
@@ -51,6 +52,7 @@ import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter
  * 
  * @author Phillip Webb
  * @author Dave Syer
+ * @author Oliver Gierke
  */
 public abstract class JpaBaseConfiguration implements BeanFactoryAware, EnvironmentAware {
 
@@ -64,14 +66,16 @@ public abstract class JpaBaseConfiguration implements BeanFactoryAware, Environm
 	}
 
 	@Bean
+	@ConditionalOnMissingBean(PlatformTransactionManager.class)
 	public PlatformTransactionManager transactionManager() {
-		return new JpaTransactionManager(entityManagerFactory().getObject());
+		return new JpaTransactionManager();
 	}
 
 	@Bean
-	public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
+	@ConditionalOnMissingBean(EntityManagerFactoryInfo.class)
+	public LocalContainerEntityManagerFactoryBean entityManagerFactory(JpaVendorAdapter jpaVendorAdapter) {
 		LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
-		entityManagerFactoryBean.setJpaVendorAdapter(jpaVendorAdapter());
+		entityManagerFactoryBean.setJpaVendorAdapter(jpaVendorAdapter);
 		entityManagerFactoryBean.setDataSource(getDataSource());
 		entityManagerFactoryBean.setPackagesToScan(getPackagesToScan());
 		entityManagerFactoryBean.getJpaPropertyMap().putAll(
@@ -81,6 +85,7 @@ public abstract class JpaBaseConfiguration implements BeanFactoryAware, Environm
 	}
 
 	@Bean
+	@ConditionalOnMissingBean(JpaVendorAdapter.class)
 	public JpaVendorAdapter jpaVendorAdapter() {
 		AbstractJpaVendorAdapter adapter = createJpaVendorAdapter();
 		adapter.setShowSql(this.environment.getProperty("show-sql", Boolean.class, true));
diff --git a/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/orm/jpa/AbstractJpaAutoConfigurationTests.java b/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/orm/jpa/AbstractJpaAutoConfigurationTests.java
index e3bfcfae4d3..106957b7ffb 100644
--- a/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/orm/jpa/AbstractJpaAutoConfigurationTests.java
+++ b/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/orm/jpa/AbstractJpaAutoConfigurationTests.java
@@ -16,6 +16,7 @@
 
 package org.springframework.boot.autoconfigure.orm.jpa;
 
+import java.util.Collections;
 import java.util.Map;
 
 import javax.sql.DataSource;
@@ -27,6 +28,7 @@ import org.springframework.boot.autoconfigure.ComponentScanDetectorConfiguration
 import org.springframework.boot.autoconfigure.PropertyPlaceholderAutoConfiguration;
 import org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration;
 import org.springframework.boot.autoconfigure.jdbc.EmbeddedDataSourceConfiguration;
+import org.springframework.boot.autoconfigure.orm.jpa.AbstractJpaAutoConfigurationTests.TestConfigurationWithTransactionManager.CustomJpaTransactionManager;
 import org.springframework.boot.autoconfigure.orm.jpa.test.City;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
@@ -34,11 +36,14 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.orm.jpa.JpaTransactionManager;
+import org.springframework.orm.jpa.JpaVendorAdapter;
 import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
 import org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter;
 import org.springframework.orm.jpa.support.OpenEntityManagerInViewInterceptor;
+import org.springframework.transaction.PlatformTransactionManager;
 import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
 
+import static org.hamcrest.CoreMatchers.*;
 import static org.hamcrest.Matchers.equalTo;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
@@ -130,9 +135,35 @@ public abstract class AbstractJpaAutoConfigurationTests {
 		assertThat(map.get("a"), equalTo((Object) "b"));
 		assertThat(map.get("c"), equalTo((Object) "d"));
 	}
+	
+	@Test
+	public void usesManuallyDefinedEntityManagerFactoryBeanIfAvailable() {
+		
+		setupTestConfiguration(TestConfigurationWithEntityManagerFactory.class);
+		this.context.refresh();
+		
+		LocalContainerEntityManagerFactoryBean factoryBean = this.context.getBean(LocalContainerEntityManagerFactoryBean.class);
+		Map<String, Object> map = factoryBean.getJpaPropertyMap();
+		assertThat(map.get("configured"), is((Object) "manually"));
+	}
+	
+	@Test
+	public void usesManuallyDefinedTransactionManagerBeanIfAvailable() {
+		
+		setupTestConfiguration(TestConfigurationWithTransactionManager.class);
+		this.context.refresh();
+		
+		PlatformTransactionManager txManager = this.context.getBean(PlatformTransactionManager.class);
+		assertThat(txManager, is(instanceOf(CustomJpaTransactionManager.class)));
+	}
 
 	protected void setupTestConfiguration() {
-		this.context.register(TestConfiguration.class,
+		setupTestConfiguration(TestConfiguration.class);
+	}
+	
+	protected void setupTestConfiguration(Class<?> configClass) {
+		
+		this.context.register(configClass,
 				ComponentScanDetectorConfiguration.class,
 				EmbeddedDataSourceConfiguration.class,
 				PropertyPlaceholderAutoConfiguration.class, getAutoConfigureClass());
@@ -156,7 +187,34 @@ public abstract class AbstractJpaAutoConfigurationTests {
 		public OpenEntityManagerInViewFilter openEntityManagerInViewFilter() {
 			return new OpenEntityManagerInViewFilter();
 		}
-
 	}
-
+	
+	@Configuration
+	protected static class TestConfigurationWithEntityManagerFactory extends TestConfiguration {
+		
+		@Bean
+		public LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource, JpaVendorAdapter adapter) {
+			
+			LocalContainerEntityManagerFactoryBean factoryBean = new LocalContainerEntityManagerFactoryBean();
+			factoryBean.setJpaVendorAdapter(adapter);
+			factoryBean.setDataSource(dataSource);
+			factoryBean.setPersistenceUnitName("manually-configured");
+			factoryBean.setJpaPropertyMap(Collections.singletonMap("configured", "manually"));
+			return factoryBean;
+		}
+	}
+	
+	@Configuration
+	@ComponentScan(basePackageClasses = { City.class })
+	protected static class TestConfigurationWithTransactionManager {
+		
+		@Bean
+		public PlatformTransactionManager transactionManager() {
+			return new CustomJpaTransactionManager();
+		}
+		
+		static class CustomJpaTransactionManager extends JpaTransactionManager {
+			
+		}
+	}
 }
diff --git a/spring-boot-autoconfigure/src/test/resources/META-INF/persistence.xml b/spring-boot-autoconfigure/src/test/resources/META-INF/persistence.xml
new file mode 100644
index 00000000000..1607abfb578
--- /dev/null
+++ b/spring-boot-autoconfigure/src/test/resources/META-INF/persistence.xml
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
+	<persistence-unit name="manually-configured">
+		<class>org.springframework.boot.autoconfigure.orm.jpa.test.City</class>
+		<exclude-unlisted-classes>true</exclude-unlisted-classes>
+	</persistence-unit>
+</persistence>