[One (M9) Original Android Development] adlx.xda:
Here's the changelog since 12/04/2015, which I believe was the last Official CM12.1

Changelog:

Project android

0749a80 default.xml: android-5.1.1_r34 -> android-5.1.1_r35

e999c31 Deprecate CMAccount

54803b7 default.xml: Update AOSP tag to android-5.1.1_r34

b518a5c manifest: Remove whispersystems (EOL Feb 1)

f4e3856 Use clone-depth="1" for all pre-built projects.

987f1ed default.xml: Update AOSP tag to android-5.1.1_r33

Project build

0e60de2 build: force .config update if additional kernel config changes

e6f8b55 kernel: Fix usage of KERNEL_ARCH

937d315 mms: introduce a shortcut to quickly rebuild kernel/boot.img

9d72f25 kernel: prevent targets from being rebuilt needlessly

e2f515a kernel: don't build modules or dtbs unless enabled

fa1323c "LMY49H"

fafe789 Updating security patch string to 2016-03-01

45182dc LMY49G

11a5628 "LMB78"

98e29ea "LMY49F"

d9a7c8e "LMB78"

9492d27 "LMY49E"

f28a559 "LMY49D"

5c8bd52 DO NOT MERGE - Update security string to 2016-02-01

5bb2f1a Update security string to 2015-12-01 - DO NOT MERGE

Project cts

0044895 DO NOT MERGE security: Test OOB arbitrary write at AMessage::FromParcel

Project development

5b7533d idegen: don't use hardcoded out directory

Project device/htc/hima-common

0d5a302 hima: Rename Broadcom HCD file

Project device/oppo/msm8974-common

a253ba8 msm8974: Allow flashing with newer TrustZone version

4821411 lights: fix battery light not turning off

92cbadb lights: Cleanup the code

Project external/bluetooth/bluedroid

412741c bnep_utils: remove correct duplicate else statement

b42291d bnep_utils: remove duplicate else statement

575cb99 [PATCH] DO NOT MERGE - Add proper checks for PAN & BNEP in BD stack

Project external/conscrypt

e653c2d Prevent duplicate certificates in TrustedCertificateIndex

e2db202 Cache intermediate CA separately

Project external/ffmpeg

7436342 Add MODULE_LICENSE and NOTICE files

Project external/iproute2

b1ad646 Add MODULE_LICENSE and NOTICE files

Project external/iptables

a83a9a0 Add MODULE_LICENSE and NOTICE files

Project external/koush/ion

4204efc Ion: Add .flv file type

Project external/libhevc

e4ec892 Fix the frame size alignments

9dc6202 Fix the frame size alignments

Project external/libpng

f3e5faa libpng: fix hang during read when inflate fails

Project external/libvpx

5a9753f Merge Conflict Fix CL to lmp-mr1-release for ag/849478

Project external/skia

635c2b9 [PATCH] Purge non-NEON ARM code. DO NOT MERGE

Project frameworks/av

c841410 [PATCH 6/6] GenericSource: reset mDecryptHandle when mDataSource is cleared.

6ad0c98 Merge Conflict Addressed.

5a67887 DO NOT MERGE - Remove deprecated image defines

fe84c20 Fix out-of-bounds write

b862285 fix possible overflow in effect wrappers.

3e49ad2 GenericSource: reset mDrmManagerClient when mDataSource is cleared.

3292bef DO NOT MERGE - libstagefright: check requested memory size before allocation for SoftMPEG4Encoder and SoftVPXEncoder.

0077bdf DO NOT MERGE nuplayer: do not use cached source for wvm content

6616d19 DO NOT MERGE SoundPool: add lock for findSample access from SoundPoolThread

d42eea9 DO NOT MERGE - OMX: allow only secure codec to remotely call allocateBuffer.

2f8a273 stagefright: check bounds for MediaCodecList.getCodecInfo

2ee14e7 DO NOT MERGE - AudioFlinger: Clear record buffers when starting RecordThread

92d92ff ID3: check possible integer overflow for extendedHeaderSize and paddingSize.

09ac69b Check NAL size before use

aded9bd MPEG4Extractor: ensure buffer size is not less than 8 for LastCommentData.

91f54ae Don't crash when there's no conceal frame

d7d445d stagefright: fix AMessage::FromParcel

c1432cb DO NOT MERGE Fix vulnerability in mediaserver

9b68cec DO NOT MERGE NuCachedSource2: fix possible erroneous early free

cf1338a Limit allocations to avoid out-of-memory

Project frameworks/base

7215c2e fix metrics density comparisons

fda88fd SysUI: Fix hiding sensitive notification behavior

fb22fe5 SysUI: Fix hiding per-app sensitive notifications

56eaddf SharedStorageAgent: fix off by 1

69da9d9 Fonts: add sans-serif fallback fonts first

3c12795 SettingsProvider: allow ambient display/doze mode to be overlayed

4d7ad43 SettingsProvider: Allow default volume adjust sound to be overlayed.

e21c3d2 SysUI: Keep sensitive notifications redacted for swipe

a823e58 Add ability to set preconfirmed apps filter for immersive mode hint

e7f34ea SystemUI: Handle possible NPE on task.group during layout.

9ccd025 bootanimation: Move the bootanimation playaudio code

b475e3b LiveDisplayTile : Update entries on locale changes

4aae432 SystemUI : Show create profile if user doesn't have one setup

47e7161 AppOps: fix wifi scan op

9a56b44 Paella: Enable Spanish single shift table

1e60f9b StrictMode: fix deserialization of ViolationInfo on large stacks

e8ef090 policy: disable EdgeGestureService

610a2bd Fingerprint: fix restarting timeout when screen is on

af416e3 fingerprint improvements

d92368f ThemeService: ManagedProvisioning is a setup package too.

9b84965 Make WIFI_IDLE_MS default into an overlay

75baf57 SettingsProvider: Load notification led customization defaults

f95b627 Fingerprint: handle canclled error code

a22cfa7 ThemeEngine : Use manifest.mf for hash calculation

ea360f8 NavigationBar : Switch to display orientation from config orientation

326bf74 Add custom camera shutter

21ddba5 PowerManagerService: Log when proximity blocks wake

78b287e SystemUI: fix "directly show bouncer" conflicting with smart unlock

eedcc4f Fix lockscreen disabling for MSIM.

ef53d61 DO NOT MERGE. Prevent recents from coming up when in SUW

a1734f0 DO NOT MERGE Ensure that the device is provisioned before showing Recents.

667b1d2 Toast: Fix toast layout for RTL

1ddc07d [PATCH 2/2] Delay hiding the cast icon for 3 seconds. DO NOT MERGE

88f1378 [PATCH 1/2] DO NOT MERGE Send next alarm's show intent via PendingIntent

Project frameworks/minikin

ed4c8d7 Avoid integer overflows in parsing fonts