diff --git a/src/System.Reflection.Metadata/src/Resources/Strings.resx b/src/System.Reflection.Metadata/src/Resources/Strings.resx
index 830e1e557f9d..2e42af0cb46c 100644
--- a/src/System.Reflection.Metadata/src/Resources/Strings.resx
+++ b/src/System.Reflection.Metadata/src/Resources/Strings.resx
@@ -426,6 +426,9 @@
   <data name="HashTooShort" xml:space="preserve">
     <value>Hash must be at least {0}B long.</value>
   </data>
+  <data name="UnexpectedArrayLength" xml:space="preserve">
+    <value>Expected array of length {0}.</value>
+  </data>
   <data name="ValueMustBeMultiple" xml:space="preserve">
     <value>Value must be multiple of {0}.</value>
   </data>
diff --git a/src/System.Reflection.Metadata/src/System/Reflection/Metadata/BlobContentId.cs b/src/System.Reflection.Metadata/src/System/Reflection/Metadata/BlobContentId.cs
index 1d6d9ab4a918..5ae3e82be900 100644
--- a/src/System.Reflection.Metadata/src/System/Reflection/Metadata/BlobContentId.cs
+++ b/src/System.Reflection.Metadata/src/System/Reflection/Metadata/BlobContentId.cs
@@ -10,6 +10,8 @@ namespace System.Reflection.Metadata
 {
     public struct BlobContentId
     {
+        private const int Size = BlobUtilities.SizeOfGuid + sizeof(uint);
+
         public Guid Guid { get; }
         public uint Stamp { get; }
 
@@ -19,6 +21,31 @@ public BlobContentId(Guid guid, uint stamp)
             Stamp = stamp;
         }
 
+        public BlobContentId(ImmutableArray<byte> id) 
+            : this(ImmutableByteArrayInterop.DangerousGetUnderlyingArray(id))
+        {
+        }
+
+        public unsafe BlobContentId(byte[] id)
+        {
+            if (id == null)
+            {
+                throw new ArgumentNullException(nameof(id));
+            }
+
+            if (id.Length != Size)
+            {
+                throw new ArgumentException(SR.Format(SR.UnexpectedArrayLength, Size), nameof(id));
+            }
+
+            fixed (byte* ptr = id)
+            {
+                var reader = new BlobReader(ptr, id.Length);
+                Guid = reader.ReadGuid();
+                Stamp = reader.ReadUInt32();
+            }
+        }
+
         public bool IsDefault => Guid == default(Guid) && Stamp == 0;
 
         public static BlobContentId FromHash(ImmutableArray<byte> hashCode)
diff --git a/src/System.Reflection.Metadata/tests/Metadata/BlobContentIdTests.cs b/src/System.Reflection.Metadata/tests/Metadata/BlobContentIdTests.cs
index c8dcba134325..15107a5d10a7 100644
--- a/src/System.Reflection.Metadata/tests/Metadata/BlobContentIdTests.cs
+++ b/src/System.Reflection.Metadata/tests/Metadata/BlobContentIdTests.cs
@@ -22,9 +22,25 @@ public void Ctor()
             Assert.Equal(0x12345678u, id2.Stamp);
             Assert.False(id2.IsDefault);
 
+            var id3 = new BlobContentId(new byte[] { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, 0x13, 0x14 });
+            Assert.Equal(new Guid("04030201-0605-0807-090a-0b0c0d0e0f10"), id3.Guid);
+            Assert.Equal(0x14131211u, id3.Stamp);
+            Assert.False(id3.IsDefault);
+
             Assert.True(default(BlobContentId).IsDefault);
         }
 
+        [Fact]
+        public void Ctor_Errors()
+        {
+            Assert.Throws<ArgumentNullException>("id", () => new BlobContentId(null));
+            Assert.Throws<ArgumentNullException>("id", () => new BlobContentId(default(ImmutableArray<byte>)));
+            Assert.Throws<ArgumentException>("id", () => new BlobContentId(ImmutableArray.Create<byte>()));
+            Assert.Throws<ArgumentException>("id", () => new BlobContentId(ImmutableArray.Create<byte>(0)));
+            Assert.Throws<ArgumentException>("id", () => new BlobContentId(ImmutableArray.Create<byte>(0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, 0x13)));
+            Assert.Throws<ArgumentException>("id", () => new BlobContentId(ImmutableArray.Create<byte>(0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15)));
+        }
+
         [Fact]
         public void FromHash()
         {