diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index ad8a41be68..2417943240 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -1047,6 +1047,10 @@
     <apic/>
     <hap/>
     <privnet/>
+    <hyperv>
+      <relaxed state='on'>
+    </hyperv>
+
   </features>
   ...</pre>
 
@@ -1087,6 +1091,23 @@
         This feature is only relevant for container based
         virtualization drivers, such as LXC.
       </dd>
+      <dt><code>hyperv</code></dt>
+      <dd>Enable various features improving behavior of guests
+        running Microsoft Windows.
+      <table class="top_table">
+        <tr>
+          <th>Feature</th>
+          <th>Description</th>
+          <th>Value</th>
+        </tr>
+        <tr>
+          <td>relaxed</td>
+          <td>Relax contstraints on timers</td>
+          <td> on, off</td>
+        </tr>
+      </table>
+      <span class="since">Since 1.0.0 (QEMU only)</span>
+      </dd>
     </dl>
 
     <h3><a name="elementsTime">Time keeping</a></h3>
diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index 70bc0e207d..17ad86b907 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -2946,7 +2946,8 @@
     </element>
   </define>
   <!--
-      A set of optional features: PAE, APIC, ACPI, and HAP support
+      A set of optional features: PAE, APIC, ACPI,
+      HyperV Enlightenment and HAP support
     -->
   <define name="features">
     <optional>
@@ -2979,6 +2980,9 @@
               <empty/>
             </element>
           </optional>
+          <optional>
+            <ref name="hyperv"/>
+          </optional>
           <optional>
             <element name="viridian">
               <empty/>
@@ -3434,6 +3438,28 @@
     </element>
   </define>
 
+  <!-- Optional HyperV Enlightenment features -->
+  <define name="hyperv">
+    <element name="hyperv">
+      <interleave>
+        <optional>
+          <element name="relaxed">
+            <ref name="hypervtristate"/>
+          </element>
+        </optional>
+      </interleave>
+    </element>
+  </define>
+
+  <define name="hypervtristate">
+    <attribute name="state">
+      <choice>
+        <value>on</value>
+        <value>off</value>
+      </choice>
+    </attribute>
+  </define>
+
   <!--
        Optional hypervisor extensions in their own namespace:
          QEmu
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index b6bb080087..7d38114d83 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -113,13 +113,17 @@ VIR_ENUM_IMPL(virDomainFeature, VIR_DOMAIN_FEATURE_LAST,
               "pae",
               "hap",
               "viridian",
-              "privnet")
+              "privnet",
+              "hyperv")
 
 VIR_ENUM_IMPL(virDomainFeatureState, VIR_DOMAIN_FEATURE_STATE_LAST,
               "default",
               "on",
               "off")
 
+VIR_ENUM_IMPL(virDomainHyperv, VIR_DOMAIN_HYPERV_LAST,
+              "relaxed")
+
 VIR_ENUM_IMPL(virDomainLifecycle, VIR_DOMAIN_LIFECYCLE_LAST,
               "destroy",
               "restart",
@@ -9074,6 +9078,53 @@ static virDomainDefPtr virDomainDefParseXML(virCapsPtr caps,
         VIR_FREE(nodes);
     }
 
+    if (def->features & (1 << VIR_DOMAIN_FEATURE_HYPERV)) {
+        int feature;
+        int value;
+        node = ctxt->node;
+        if ((n = virXPathNodeSet("./features/hyperv/*", ctxt, &nodes)) < 0)
+            goto error;
+
+        for (i = 0; i < n; i++) {
+            feature = virDomainHypervTypeFromString((const char *)nodes[i]->name);
+            if (feature < 0) {
+                virReportError(VIR_ERR_XML_ERROR,
+                               _("unsupported HyperV Enlightenment feature: %s"),
+                               nodes[i]->name);
+                goto error;
+            }
+
+            ctxt->node = nodes[i];
+
+            switch ((enum virDomainHyperv) feature) {
+                case VIR_DOMAIN_HYPERV_RELAXED:
+                    if (!(tmp = virXPathString("string(./@state)", ctxt))) {
+                        virReportError(VIR_ERR_XML_ERROR,
+                                       _("missing 'state' attribute for "
+                                         "HyperV Enlightenment feature '%s'"),
+                                       nodes[i]->name);
+                        goto error;
+                    }
+
+                    if ((value = virDomainFeatureStateTypeFromString(tmp)) < 0) {
+                        virReportError(VIR_ERR_XML_ERROR,
+                                       _("invalid value of state argument "
+                                         "for HyperV Enlightenment feature '%s'"),
+                                       nodes[i]->name);
+                        goto error;
+                    }
+
+                    def->hyperv_features[feature] = value;
+                    break;
+
+                case VIR_DOMAIN_HYPERV_LAST:
+                    break;
+            }
+        }
+        VIR_FREE(nodes);
+        ctxt->node = node;
+    }
+
     if (virDomainEventActionParseXML(ctxt, "on_reboot",
                                      "string(./on_reboot[1])",
                                      &def->onReboot,
@@ -13817,7 +13868,7 @@ virDomainDefFormatInternal(virDomainDefPtr def,
     if (def->features) {
         virBufferAddLit(buf, "  <features>\n");
         for (i = 0 ; i < VIR_DOMAIN_FEATURE_LAST ; i++) {
-            if (def->features & (1 << i)) {
+            if (def->features & (1 << i) && i != VIR_DOMAIN_FEATURE_HYPERV) {
                 const char *name = virDomainFeatureTypeToString(i);
                 if (!name) {
                     virReportError(VIR_ERR_INTERNAL_ERROR,
@@ -13833,6 +13884,25 @@ virDomainDefFormatInternal(virDomainDefPtr def,
                 virBufferAddLit(buf, "/>\n");
             }
         }
+
+        if (def->features & (1 << VIR_DOMAIN_FEATURE_HYPERV)) {
+            virBufferAddLit(buf, "    <hyperv>\n");
+            for (i = 0; i < VIR_DOMAIN_HYPERV_LAST; i++) {
+                switch ((enum virDomainHyperv) i) {
+                case VIR_DOMAIN_HYPERV_RELAXED:
+                    if (def->hyperv_features[i])
+                        virBufferAsprintf(buf, "      <%s state='%s'/>\n",
+                                          virDomainHypervTypeToString(i),
+                                          virDomainFeatureStateTypeToString(def->hyperv_features[i]));
+                    break;
+
+                case VIR_DOMAIN_HYPERV_LAST:
+                    break;
+                }
+            }
+            virBufferAddLit(buf, "    </hyperv>\n");
+        }
+
         virBufferAddLit(buf, "  </features>\n");
     }
 
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index ed53d4487d..ac6311fc6a 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -1385,6 +1385,7 @@ enum virDomainFeature {
     VIR_DOMAIN_FEATURE_HAP,
     VIR_DOMAIN_FEATURE_VIRIDIAN,
     VIR_DOMAIN_FEATURE_PRIVNET,
+    VIR_DOMAIN_FEATURE_HYPERV,
 
     VIR_DOMAIN_FEATURE_LAST
 };
@@ -1397,6 +1398,12 @@ enum virDomainFeatureState {
     VIR_DOMAIN_FEATURE_STATE_LAST
 };
 
+enum virDomainHyperv {
+    VIR_DOMAIN_HYPERV_RELAXED = 0,
+
+    VIR_DOMAIN_HYPERV_LAST
+};
+
 enum virDomainLifecycleAction {
     VIR_DOMAIN_LIFECYCLE_DESTROY,
     VIR_DOMAIN_LIFECYCLE_RESTART,
@@ -1710,6 +1717,8 @@ struct _virDomainDef {
     int features;
     /* enum virDomainFeatureState */
     int apic_eoi;
+    /* These options are of type virDomainFeatureState */
+    int hyperv_features[VIR_DOMAIN_HYPERV_LAST];
 
     virDomainClockDef clock;
 
@@ -2239,6 +2248,7 @@ VIR_ENUM_DECL(virDomainGraphicsSpiceClipboardCopypaste)
 VIR_ENUM_DECL(virDomainGraphicsSpiceMouseMode)
 VIR_ENUM_DECL(virDomainNumatuneMemMode)
 VIR_ENUM_DECL(virDomainNumatuneMemPlacementMode)
+VIR_ENUM_DECL(virDomainHyperv)
 /* from libvirt.h */
 VIR_ENUM_DECL(virDomainState)
 VIR_ENUM_DECL(virDomainNostateReason)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 0801c6c558..1a0c2f6ce7 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -406,6 +406,8 @@ virDomainHostdevRemove;
 virDomainHostdevSubsysTypeToString;
 virDomainHubTypeFromString;
 virDomainHubTypeToString;
+virDomainHypervTypeFromString;
+virDomainHypervTypeToString;
 virDomainInputDefFree;
 virDomainIoEventFdTypeFromString;
 virDomainIoEventFdTypeToString;